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T.I  r?rfc.VRY 

Class  j\o.^o^^3 .... 
CosL..^5 

|||,i,i,j7T77,i, ,i|i|iTnTPii|ii'|i|i|i|i|i|i|i|r|l|iii|i|i|i|i,i|r,i,i; 


^7  9 


BOOK    630.G79   c   1 


AGRICULTURE 


....  .11 


ELEMENTS  U*5|^^ 

^3 


SCIENTIFIC    AND    PRACTICAL 


AGRICULTURE, 


OR    THE 

APPLICATION  OF    BIOLOfeY,  GEOLOGY  AND    CHEMISTRY    TO 
AGRICULTURE  AND  HORTICULTURE. 


INTENDED  AS  A  TEXT-BOOK   FOR 


FARMERS  AND  STUDENTS  IN  AGRICULTURE. 


/&,r,sr/A 


BY  ALONZO  GRAY,  A.  M. 

Author  of  Elements  of  Chemistry,  and  Teacher  of  Chemistry  and  Natural  History 
in  Phillips  Academy,  Andover,  Mass. 


ANDOVER: 

ALLEN,  MORRILL   AND   WARDWELL. 

NEW  YORK : 

DAYTON    AND    NEWMAN. 

1842. 


^^-^ 


# 

Entered  according  to  Act  of  Congress,  in  the  year  1842,  by 

ALONZO  GRAY, 
in  the  Clerk's  Office  of  the  District  Court  of  Massachusetts. 


'•*''«^.^,«^% 


PREFACE 


About  two  years  since,  the  author  turned  his  attention  to 
Agricultural  Chemistry,  with  a  view  to  prepare  a  text-book 
on  scientific  and  practical  Agriculture.  His  particular  ob- 
ject was,  to  furnish  facilities  for  the  introduction  of  Agricul- 
ture, as  a  branch  of  study,  into  some  of  our  academies  and 
high  schools.  This  design  has  been  steadily  pursued ;  al- 
though, at  the  time  of  commencing  his  investigations,  the 
subject  was  involved  in  so  much  obscurity  and  uncertainty, 
that  he  often  despaired  of  being  able  to  prepare  a  book,  which 
would  be  of  any  real  service  to  those  for  whom  it  was  in- 
tended. 

The  late  works  of  Liebig,  Daubeny,  Johnston  and  Dana, 
together  with  the  Geological  Reports,  in  most  of  the  States, 
have  thrown  a  flood  of  light  over  the  whole  subject ;  and 
although  we  cannot  affirm  that  all  is  known  which  it  is  de- 
sirable to  know,  still,  many  fundamental  principles  are  estab- 
lished ;  and  we  have  the  materials  for  constructing  the  most 
important  and  useful  science  of  modern  times. 

The  avidity  with  which  the  public  mind  have  seized  every- 
thing which  promised  to  throw  light  on  the  art  of  husbandry, 
is  an  encouraging  indication,  that  it  begins  to  appreciate  the 
vast  importance  of  the  subject. 

The  fact,  that  many  gentlemen  of  education  and  fortune  are 
resorting  to  this  primitive  art,  as  a  means  of  pleasure  or  for 
scientific  purposes,  still  further  shows,  both  the  dignity  of  the 
employment,  and  its  power   of  aflTording   those  simple  and 


IV  PREFACE. 

satisfying  pleasures,  which  cannot  be  derived  from  mercantile 
or  professional  pursuits. 

In  view  of  such  considerations,  the  author  has  been  deeply 
impressed  with  the  desirableness  of  furnishing  the  young  far- 
mer with  a  scientific  knowledge  of  his  profession.  This  is 
especially  desirable,  in  order  to  give  dignity  and  attractive- 
ness to  the  employment.  A  thorough  knowledge  of  the 
fundamental  principles  upon  which  the  art  is  based,  seems 
almost  essential  to  successful  practice.  This  necessity  is 
yearly  becoming  more  and  more  imperative. 

The  States,  generally,  have  made  ample  provision  for  the 
education  of  their  sons,  in  almost  every  branch  of  knowledge, 
with  the  exception  of  that,  upon  which  the  profession  of  the 
majority  is  based.  The  art  on  which  all  depend,  and  which 
the  great  body  of  the  people  practice,  is  left  without  any 
professional  instruction,  either  public  or  private. 

To  supply,  in  some  degree,  this  glaring  deficiency  in  our 
popular  system  of  education,  and  to  call  the  attention  of  those 
who  are  interested  in  the  prosperity  of  our  free  institutions, 
to  the  importance  of  having  the  sons  of  republicans  well  in- 
structed in  this  most  noble  art,  have  been  the  principal  in- 
ducements, for  giving  this  work  to  the  public  in  its  present 
form.  For  we  are  fully  persuaded,  that  Agriculture  will 
never  be  held  in  that  high  estimation  which  it  deserves  to  be  ; 
that  it  will  never  attain  to  that  perfection  of  which  it  is  sus- 
ceptible ;  until  it  is  made  a  regular  branch  of  study  by  those 
who  practice  it  as  a  profession  ;  until  it  is  incorporated  into 
our  systems  of  education. 

But  although  this  work  is  designed  for  students  in  Agricul- 
ture ;  it  is  not  intended  to  be  studied  exclusively  by  those, 
who  are  attending  at  some  public  institution.  It  is  designed 
for  the  farmer,  at  whatever  stage  of  his  education  he  may 
have  arrived ;  for  we  believe  that  it  is  as  true  of  farmers,  as 
of  any  other  class  of  men,  that  they  are  "never  too  old  to 


PREFACE.  V 

learn  ;"  and  that,  unless  they  are  very  stupid,  they  generally 
do  learn  something  new  every  day  of  their  lives. 

It  has  been  necessary,  to  introduce  many  terms  of  a  tech- 
nical character,  but  none  are  used  which  have  not  been  de- 
fined, or  whose  signification  may  not  be  discerned  by  a  care- 
ful examination.  We  trust,  therefore,  that  the  farmer  will 
not  be  deterred  from  reading  the  work,  because  he  may  find 
words  belonging  to  sciences  which  are  unknown  to  him.  If 
he  will  not  only  read  the  book,  but  study  it,  and  that  too 
in  course,  we  venture  to  assure  him,  that  he  shall  be  able  to 
understand  what  is  written,  whether  he  is  benefited  by  it 
or  not. 

In  the  preparation  of  the  work,  the  author  has  consulted 
several  writers  on  Agricultural' Chemistry,  particularly  Sir  H. 
Davy,  Chaptal,  Sinclair,  Liebig,  Daubeny,  Johnston  and  Da- 
na ;  and  also,  various  Reports  and  periodical  publications. 
The  view^s  of  each  writer,  on  many  important  points,  have 
been  presented,  and  their  theories  examined. 

In  addition  to  an  Index,  a  very  full  Table  of  Contents  is  add- 
ed. This  table  is  intended  to  contain  a  complete  analysis  of 
the  work,  in  the  form  of  topics.  The  design  of  this  table  is,  to 
fiirnish  the  student  with  the  most  important  subjects  for  his 
attention  ;  and,  should  the  work  ever  be  so  fortunate,  as  to 
be  introduced  as  a  text-book  into  cur  academies,  these  topics 
may  serve  the  purpose  of  direct  questions. 

It  is  proper,  in  this  place,  for  the  author  to  acknowledge 
his  particular  obligations  to  Dr.  Samuel  L.  Dana  of  Lowell, 
for  the  many  kind  suggestions  which  he  has  made  from 
time  to  time,  and  for  the  important  aid  afforded  by  his  late 
work  ;  although  not  received,  until  nearly  the  whole  of  this 
work  was  prepared  for  the  press. 

The  author  would  also  express  his  obligations  to  the  Trus- 
tees of  Phillips  Academy,  who  have  so  promptly  responded  to 
the  suggestion  of  preparing  a  text-book  for  the  use  of  the  In- 
1* 


Vi  PREFACE. 

stitution  under  their  care;  and  who  have  afforded  him  many 
facilities  for  bringing  the  work  to  a  close  at  so  early  a  date. 

With  the  hope  that  this  effort  to  improve  our  system  of 
rural  economy  will  meet  with  that  success  which  is  so  ear- 
nestly desired,  the  author  would  now  commit  these  results 
of  his  studies  to  the  better  judgment  of  those  who  may  be 
induced  to  read  what  is  herein  written. 

A.  G. 

Encr.  Depart,  in  Phillips  Academy,  ) 
*     Andover,  April,  1842.  > 


TABLE  OF  CONTENTS. 


INTRODUCTION. 

Page. 
Agriculture  defined — its  importance 17 

Aid  which  it  may  derive  from  the  Natural  sciences     .         .         .18 

I.  Mineralogy  and  Geology 18 

II.  Chemistry 19 

III.  Botany 24 

Plan  of  the  Work     ■ 25 

Influence  of  slight  improvements 26 

BIOLOGY  OF  PLANTS. 

CHAPTER  I.— The  Vital  Principle, 
Division  of  Natural  bodies 29 

Sect.  1.  Definitions  and  descriptions — proofs^  nature  and  uses  of  the 
Vital  Principle. 

Definition  of  Biology 29 

Of  an  organized  body             30 

Definition  of  a  plant 30 

Tissue  defined  and  described 30 

Cells 30 

Spiral  vessels — Pores — Cuticle — Wood        .        •         .         .         .  31 
Cambium,  Alburnum,  Assimilation,  Transpiration       .         .         .38 

Comparison  of  the  Vital  Principle  in  animals  and  plants       .         .  33 
Proofs  of  the  existence  of  Vitality. 

I.  Power  of  vegetables  to  resist  natural  laws — 1.  Chemical  affini- 
ty.    2.  Gravity.     3.  Heat  and  Cold 35 

II.  Excitability  in  vegetables. — 1.  Influence  of  light.     2.  Of  heat     36 
3.  Of  electricity.     4.  Of  artificial  stimulants     .         .         .         .37 

III.  Irritability  of  vegetables         .......     37 

IV.  Productions  of  the  vegetable  kingdom  .         .         .         .37 

JVature  of  Vitality — Biological  hypotheses 38 

Definition  of  life 39 


Vm  CONTENTS. 

Uses  of  the  vital  principle 40 

1.  J'^3  relations  to  agriculture  as  a  science     .         .         .         .         .40 

2.  Its  relations  to  Natural  Tlicology 41 

3.  Moral  effect  of  considering  this  power 43 

Sect.  2.  Definitions. — Conditions  necessary  to  develope  the  Vital 
Prmciple  in  the  seed,  bulb  and  bud. 

Definitions — 1.  Of  eeed 43 

,2.  Of  cotyledons.    3.  Radicle.    4.  Plumala.    5.  Bulbs.    6.  Buds  44 
7.  Eyes.     8.  Chemical  transformations — catalytic  force.     9.  Of 

a  simple  substance          ........  45 

10.  Of  Compound  bodies.     11.  Of  alkalies  and  acids.     12.  Of 

salts.     13.  Of  equivalents.     14.  Organic  constituents           .  46 

15.  Inorganic  constituents.        ...,.:.  47 

Organic  Constituents — 1.  Oxygen 47 

2.  Hydrogen — water 47 

3.  Carbon,  carbonic  acid 48 

4.  Nitrogen,  nitric  acid,  ammonia 48 

Germination — Conditions  of          .......  49 

1.  Moisture — its  influence  upon  germination    .         .         .         .49 

2.  Air                         "                       « 50 

3.  Heat                       «                        ".-...  51 

4.  Light                     "                       " 52 

Changes  during  the  process  of  germination  .         .         .         .53 

Methods  of  promoting  germination. 

1.  By  immersing  the  seeds  in  hot  water  .         .         .         .54 

2.  Experiments  by  Mr.  Bowie  .         .         .         .         .         .54 

3.  By  mixing  seeds  with  substances  which  yield  oxygen  easily  55 
Object  of  all  the  vegetable  functions — propagation;  effected  by 

seeds,  buds,  bulbs  and  leaves     .......  55 

By  cuttings,  layers  and  suckers 56 

Theory  of  the  formation  of  the  different  organs  of  plants     .  57 

Sect.  3.  Definitions — Conditions  of  the  growth  of  plants. 

Definition  1.  Of  soil 57 

2.  Of  sub-soil             58 

Organs  of  nutrition — 1.  Roots,  different  kinds  of  .         .         .58 

2.  Stem  or  culm — its  functions 58 

3.  Leaves,  their  structure  and  office 59 

4.  Flower  leaves  or  petals — their  office — analogy  between  ani- 

mal and  vegetable  bodies 60 


CONTENTS. 


IX 


Conditions  of  growth. 

I.  Proper  medium  and  space  for  growth       .         .         .         .         .61 
Uses  of  the  soil — 1.  Support 61 

2.  Repository  of  food.     3.  Chemical  changes,  medium  of        .     61 

4.  Medium  for  air,  water  and  heat  .         .         .         .         .62 

5.  Absorption  of  gases       ........     62 

II.  Food.     Supply  of  food. 

1.  Constancy  of  supply 63 

2.  Proper  regulation  ........     63 

Practical  inferences 64 

3.  Kind  of  food — nature  of 65 

III.  Tillage — Conditions  of 66 

1.  Thorough  ploughing     ........     66 

2.  Deep  ploughing,  importance  of    .         .         .         .         .         .67 

3.  Pulverizing  the  soil 68 

4.  Covering  the  seed         ........     68 

.5.  Extermination  of  weeds         .......     69 

Importance  of  the  above  conditions  illustrated       .         .         .         .70 

CHAPTER  II. 


INFLUENCE  OF  THE  ATMOSPHEKE,  WATER  AND  OTHER  AGENTS,  UPON 
THE  VITAL  PRINCIPLE,  AS  CONNECTED  WITH  THE  PHENOMENA  OF 
VEGETATION. 


Sect.  1.  JJgejicy  of  the  atmosphere. 
Composition  of  the  atmosphere     .... 
I.  Influence  of  the  oxygen  of  the  air  upon  the  roots 

Theories 

Influence  of  oxygen  upon  the  leaves  of  plants     . 

Theories 

Quantity  of  oxygen  absorbed  by  plants,  dependent, 

1.  Upon  their  vigor 

2.  Upon  temperature 

3.  Upon  the  season  of  the  year 
Quantity  absorbed  by  the  fleshy-leaved  plants 

"  "  evergreens 

"  "  herbaceous  plants 

"  "  trees  naked  during  the  winter 

Action  of  oxygen  upon  fruit  .... 

Summary  of  the  agency  of  oxygen 
II.  Influence  of  the  nitrogen  of  the  air 


72 

73 
73 

75 
76 

76 
76 
76 
76 

77 
77 
77 
78 
79 
80 


X  CONTENTS. 

III.  Influence  of  the  ammonia  of  the  atmosphere  .         .         .80 
Sources  of  ammonia. 

1.  Putrefaction  of  animal  bodies        .         .         ,         .         ,         .81 

2.  Decay  of  vegetable  substances      ......     81 

3.  Volcanoes 81 

IV.  Nitric  acid  of  the  atmosphere 82 

V.  Light  carbureted  hydrogen  83 

VI.  Influence  of  the  carbonic  acid  of  the  atmosphere  .         .     83 
Source  of  carbovic  acid. 

1.  Chemical  action 84 

2.  Combustion 84 

3.  Respiration  of  animals ■  .     84 

4.  Decay  of  vegetables 84 

Quantity  of  carbonic  acid  in  the  atmosphere       .         .         .         .84 
"W%at  becomes  of  this  acid  ? 85 

1.  It  is  decomposed  by  vegetation  .         .         .  .  .85 

2.  Quantity  of  this  acid  absorbed  at  different  periods  .  .  8G 
Other  causes  which  abstract  it  .  .  .  ,  .  .  .88 
Necessity  of  carbonic  acid  to  vegetation       .         .         .  .  .88 

VII.  Mechanical  agency  of  the  atmosphere. 

1.  Pressure 87 

2.  Medium  for  the  action  of  other  agents  .  .  .  .90 
Beautiful  and  wise  constitution  of  the  atmosphere       .         .         .91 

Sect.  2.  Agency  of  water  upon  the  vital  functions  of  plants. 

I.  Water  in  the  solid  form — ice  and  snow 02 

1.  Benefits  of  freezing  the  soil 92 

2.  Protection  afforded  the  roots  by  ice  and  snow     .         .         .92 

II.  "Water  in  the  liquid  form. 

1.  Its  solvent  properties  .......  93 

2.  Its  chemical  agency 94 

3.  Its  mechanical  agency 95 

4.  Its  agency  as  nutriment 95 

III.  Water  in  the  state  of  vapor. 

1.  Quantity  of  vapor  in  the  atmosphere  .         .  .         .96 

2.  Absorption  by  the  leaves  and  roots      ,         .         .         .         .96 

3.  Influence  in  dry  seasons      .......     97 

4.  Agency  of  dew  as  affected  by  the  conducting  power  .     97 

5.  Agency  of  rain     .........     97 

6.  Effect  of  evaporation  upon  soil  ...  .98 


CONTENTS. 


Sect.  3.  Influence  of  the  imponderable  agents  upon  the  vital  func- 
tions of  plants. 

I.  Gravity.     Experiments  of  Mr.  Knight 98 

II.  Cohesion 99 

III.  Chemical  affinity 100 

IV'.  Caloric. — Properties  necessary  to  be  studied         •         .  101 

1.  Its  influence  on  affinity 102 

2.  Effect  of  heat  in  the  spring — of  too  great  heat            .         .  102 

3.  Tendency  of  heat  to  pass  into  an  insensible  state       .         .102 

4.  Effect  of  heat  during  the  winter 103 

Distribution  of  plants  dependent  upon  temperature            .         .  104 

V.  Light.     Calorific.     Colorific  and  chemical  rays            .         .  105 

1.  Stimulating  properties  of  light 105 

2.  Its  power  in  the  decomposition  of  carbonic  acid  by  the  leaves  106 

3.  Different  colors.     Experiments  of  Mr.  Hunt     .         .         .  106 

VI.  Electricity.     Modes  of  exciting  it.     Theory        .         .         .  107 

Endosmometer,  description  of 108 

Cause  of  the  ascension  of  the  sap       ......  109 


Sect.  4.  Agency  of  man. 
Methods  by  which  men  may  control  the  imponderable  agents       111 


CHAPTER  111. 

PRODUCTIONS    OF  THE  VITAL    PRINCIPLE — THEIR  CHARACTER,  COMPO- 
SITION, SOURCES  AND  ASSIMILATION, 

Sect.  1.   Character  and  comjiosition  of  the  vegetable  productions. 

I.  Acids 117 

II.  Alkalies        .         .         . 119 

III.  Intermediate  bodies .         .  120 

IV.  Neutral  substances 123 

1.  Sugars.     2.  Amylaceous  substances           ....  124 

3.  Gums 125 

4.  Glutinous  substances 126 

Sources  of  many  articles  of  food  and  medicine      ....  126 

I.  Roots 128 

II.  JBulbs 129 

III.  Woods 130 

IV.  Leaves 130 

V.  Seeds  and  fruits            131 


XU  CONTENTS. 

Sect.   2.      Definitions  and  descriptions . — Source  and  assimilation 
of  the  organic  constituents  of  jtlants. 

Definition  and  description — ].  Of  huniin          ,         .         .         .  135 

2.  Of  humic  acid.     3.  Of  crenic  acid.     4.  Of  apocrenic  acid  136 

5.  Of  apocrenates.     6.  Extract  of  humus       ....  137 

Source  of  organic  constituents. 

I.  Carbon.     History.     Nature  of  vegetable  mould              .         ,  138 

Theories 

I.   Of  Liehig.     Arguments  in  support  of  Liebig's  theory            ,  140 

1.  Quantity  of  carbon  introduced  in  the  form  of  humate  of  lime  141 

2.  '<                                "           by  metallic  oxides       .         .  141 

3.  "                                "           by  water      ....  141 

4.  Quantity  of  carbon  yielded   by  wood  land,  meadows  and 

ploughed  fields 142 

Origin  of  the  carbon  of  the  first  vegetables     ....  142 

Quantity  in  the  atmosphere  invariable.     Why  ?     .         .        .  143 

How  is  the  carbonic  acid  of  the  atmosphere  disposed  of.?       .  143 

5.  The  most  important  function  in  the  life  of  plants— what  ?  144 

6.  Nature  of  decay— changes  which  take  place      .         .         .  144 

7.  Excrementitious  matters  of  the  roots 145 

Objections  to  Liebig's  theory. 

1.  This  theory  does  not  give  acorrect  view  of  the  humus  of  soil  146 

2.  The  facts  which  are  brought  forward  do  not  prove  it, 

allowing  them  their  full  force 146 

3.  This  theory  does  not  give  a  correct  view  of  the  quantity 

of  water  in  the  soil 147 

4.  This  theory  overlooks  the  influence  of  living  plants           .  147 

5.  There  are  evidently  other  sources  of  carbon       .         .         .148 

6.  The  theory  is  inconsistent  with  itself  and  with  facts           .  148 

7.  "  "  must  therefore  be  modified  .  .  .  .149 
Other  sources  of  carbon,  humic,  crenic  and  apocrenic  acids  ,  150 
Summary  of  the  sources  of  carbon 151 

TIteory  of  the  assimilation  of  carbon 
Illustrated  by  chemical  transformations  .         .         .         .151 

Chemical  transformations  in  plants  and  animals     .         .         .  153 

II.  Source  of  the  hydrogen  of  plants. 

1.  Water.    2.  Ammonia.     3.  Light  carbureted  hydrogen      .  155 

4.  Geine  or  humus 155 

ni.  Sources  of  the  oxygen  of  plants. 

1.  The  atmosphere.     2.  Water 155 

3.  Carbonic  acid.     4.  Geine  or  humus.     5.  Nitric  acid         .  156 


CONTENTS. 


XUI 


IV.  Theory  of  the  assimilation  of  oxygen  and  of  hydrogen      .  156 

V.  Source  and  assimilation  of  the  nitrogen  of  plants  .  .  158 
1.  The  atmosphere.  2.  Ammonia.  Proofs  .  .  .  159 
Quantity  of  nitrogen  derived  from  ammonia  ....  161 
Objections  to  Liebig's  theory  of  the  source  of  nitrogen  .  .  162 
Form  in  which  ammonia  enters  plants 163 

3.  Geine  or  humus          ........  .163 

4.  Nitric  acid,  in  the  form  of  nitrates 164 

Necessity  of  supplying  plants  with  humus      ....  165 

Sect.   3.  Definitions. — Source  and  assimilation  of  the  inorganic 
constituents  of  plants. 

Description  of  potassa,  soda,  magnesia   and  other  salts     .         .  166 

"             "    lime,  alumina,  oxide  of  iron  and  silicic  acid   .  167 

"             "    hydrochloric,  sulphuric  and  phosphoric  acids  168 

Inorganic  constituents. 

1.  Potassa,  source  and  assimilation 171 

2.  Soda,          ^^         «             « 173 

3.  Magnesia,  "         "             " 174 

4.  Lime,          u         u             a 174 

5.  Alumina,    "         "             "           ......  175 

6.  Silica.     7.  Metallic  oxides 175 

8.  Phosphoric  acid.     9.  Sulphuric  acid.     10.  Common  salt  176 


GEOLOGY  AND  CHEMISTRY  OF  SOILS. 
CHAPTER  IV. 

ROCKS  AND  THEIR  RELATION  TO  VEGETATION. 

Sect.  1.     Simple  bodies  which  compose  the  rocks. 


Sect.  2.   Compounds  formed  by  the  fourteen  simple  bodies 

I.  Primary  compounds,  or  bodies  composed  of  two  simple  bodies 
1.  Acids.    2.  Alkalies.     3.  Urets 

II.  Secondary  compounds  or  salts 

1.  Silicates 

2.  Carbonates  of  soda,  magnesia  and  potassa 

3.  Sulphates.    4.  Nitrates      .... 
5.  Phosphates.    6.  Muriates 

B 


180 
181 
181 
181 

182 
182 
183 


XIV  CONTENTS. 


Sect.  3.  Simple  jninerals  which  enter  into  the  composition  of  the 

rocks. 

1.  Quartz 183 

2.  Feldspar.     3,  Mica.     4.  Talc 184 

5.  Hornblende.  6.  Serpentine.  7.  Calcareous  spar  .  .  185 
8.  Pyrites    (fool's  gold) .186 

Sect.  4.  Composition  of  the  rocks 

1.  Igneous  and  aqueous  rocks 187 

Igneous  rocks.     1.  Granite.     2.  Gneiss.     3.  Mica  slate    .         .     187 

4.  Argillaceous  slate.  5.  Talcose  slate.  G.  Hornblende  slate  188 
7.  Graywacke.  8.  Trappean  rocks.  9.  Limestone  rocks  .  188 
10.  Sandstones 188 

Sect.  5.  Origin  of  soils. 
Agents  concerned  in  wearing  down  the  rocks     .        .         .         •     188 
1.  Oxygen.     2.  Pyrites 189 

3.  Mechanical  agency  of  water.     4.  Decaying  plants    .         .190 

5.  Growing  plants 191 

Depth  of  soil 192 


CHAPTER  V. 

SOILS,  AND  THEIR  RELATIONS  TO  VEGETATION. 

Sect.  1.  .Analysis  of  soil. 

I.  Mechanical  analysis  and  tests 195 

II.  Chemical  analysis  of  soils     .         .          .....  198 

Rules  of  analysis  by  Dr.  Dana             198 

«               "              Dr.  Jackson 198 

Sect.  2.   Composition  of  soils  as  determined  hy  analysis. 

1.  Mineral  constituents  of  soil 205 

1.  Earths. 

(1)  Silicic  acid,  its  quantity  and  of5ces           ....  205 

(2)  Aluminous  earth,  "^                   " 206 

(3)  Lime,                       «                   " 207 

(4)  Magnesia,                "                    '< 209 

2.  .Alkalies  and  metallic  oxides.     Ammonia      .         .         ,         .210 

Potassa,  quantity  and  uses, 211 

Soda  and  oxide  of  iron,  " ^        .  212 

3.  Salts  and  urets.     Common  salt 213 


CONTENTS.  XV 

Phosphate  of  alumina  and  of  lime 214 

JNitrate  of  potash   and  of  soda.     Sulphurets     ....  214 

II.   Organic  constitxicnts  of  the  soil.     Humic  acid.     Geine            .  215 

Crenic  and  apocrenic  acid.     Extract  of  humus  and  humin      .  216 

Sect.  3.     Theory  of  the  mutual  action  of  the  organic  and  inorganic 
constituents  of  soil,  and  of  groimng  vegetables. 

1.  Action  of  the  organic  and  inorganic  portions  of  soil      .          .  218 

1.  Of  silicates.     2.  Carbonates.     3.  Alkalies.     4.  Catalysis  219 

5.  Air  and  water 219 

n.  Mutual  action  of  growing  plants,  silicates,  salts,  etc.  .         .  219 

1.  General  theory  of  the  action  of  salts            ....  220 

2.  Character  of  the  acid  determines  the  peculiarity  of  effect  220 

Sect.  4.   Circumstances  upon  which  the  fertility  of  soil   depends. 

General  inferences 228 

Sect.  5.  Classification  and  description  of  soils. 
Geological  classification  of  soils. 

I.  Alluvial  soils.     1.  Of  rivers 231 

Value  of  alluviarsoils.     2.  Peat  alluvial  soils          .         .         .  232 

II.  Diluvial  soils.     1.  Sandy  and  gravelly         ....  233 
2.  Argillaceous,  clayey  and  loamy 234 

III.  Tertiary  soils.     Their  origin  and  character          .         .         .  2*34 

IV.  Secondary  soils.     1.  Cretaceous  or  chalky  soil            .         .  235 

2.  Oolitic  soil.    3.  Saliferous.    4.  Carboniferous.    5.  Silurian  236 

V.  Primary  soils 237 

1.  Argillaceous  slate  soil.     2.  Limestone  soil           .         .         .  238 

3.  Mica  slate  soil.  4.  Talcose  slate  soil  ....  239 
5.  Gneiss  soil.  6.  Granite  soil.  7.  Sienile  soil  .  .  240 
8.  Hornblende  rock  soil.     9.  Porphyry  soil    ....  241 

VI.  Trappean    soils.     1.  Greenstone.      2.  Trachyte.      3.   Lava 
soils 241 

Chemical  classification  of  soils. 

1.  Siliceous  soils.     Properties  and  mode  of  improvement           .  243 

2.  Aluminous  or  clay  soils — their  properties      ....  244 

3.  Calcareous  soils.     Properties  and  tests           ....  246 

4.  Magnesian  soils       .........  247 

5.  Peaty  soils.     Origin  of.     Properties, etc.       .         .         .         .  247 

6.  Alluvial  soils.     7.  Loamy  soils      .         .         .....  249 


XVI  CONTENTS. 

CHAPTER  VI. 

IMPROVEMENT    OF    THE    SOIL. 

Sect.  1 .   Improvement  of  the  soil  by  the  addition  of  earths. 
1.  By  carbonate  of  lime.     2.  By  sand  and  gravel      .         .         .     253 
3.  By  clay.     Theory  of  the  action  of  clay  ....     253 

Sect.  2.  Improvement  of  the  soil  by  draining  and  irrigation —  Causes 
of  wetness. 

I.  Draining.     1.  The  surface.     2.   Draining  the  soil         .         .  256 

Construction  of  drains.     Metiiod  of 257 

3.  Draining  the  sub-soil 258 

Necessity  of  draining 260 

Utility  of  draining 262 

II.  Irrigation — time  and  mode  of  watering         ....     262 

Sect.  3.  Improvement  of  the  soil  by  fallow  crops  and  by  turning  in 
green  crops. 

I.  Fallow  crops.     Naked  fallows  defined            ....    265 
Utility  of  fallow  crops 266 

II.  Turning  in  green  crops.     Process         .....     267 
Theory  of  the  action  of  green  crops 268 

Sect  4.  Rotation  or  interchange  of  crops. 
Rotation  founded  on  experience         ......     270 

Reasons  for  an  interchange  of  crops. 

I.  The  structure  of  plants 271 

1.  Culmiferous  plants.     Their  influence  in  this  respect  .     272 

2.  Leguminous  plants.     3.  Root  crops  ....    273 

II.  Composition  of  plants 273 

III.  Excretions  given  out  by  the  roots  .....  276 
Theory  of  M.  Decandolle.  Of  Macaire  Priueep  .  .  .  276 
Rules  for  constructing  a  rotation  system  .         .         .         .     278 

Sect.  5.  Root  culture — Theory  of  their  action. 
CHAPTER  VII. 

IMPROVEMENT  OF  THE   SOIL  BV  MANURES  AND  TILLAGE. 

Sect.  1 .  Mixed  manures.,  or  those  consisting  mostly  ofgeine. 
I.  Solid  excrements  of  animals.     1.  Cow  dung,  analysis  of      .     284 


CONTENTS.  XTU 

Value  of  COW  dung 285 

2.  Plorse  manure,  analysis  of          ......  286 

3.  Sheep  dung.  4.  Hog  manure.  5.  Night  soil  .  .  287 
Changes  in  fermenting  dung  heaps  .....  288 
C.  Poudrette.  7.  Guano,  analysis  of  .  .  .  .  .  293 
8.  Pigeons'  dung  and  that  of  domestic  fowls          .         .         .  297 

II.  Animal  solids — their  composition         .....     294 
1.  Horns  and  hoofs.     2.  Nails.     3.  Hair       .         ,         .         .295 

4.  Wool.     5.  Feathers.      6.  Glue.     7.  Bones,  bone  dust  and 

soot 296 

HI.  Animal  and  vegetable  bodies  destitute  of  nitrogen     .         .     297 
1.  Soap-boilers'  spent  lye,  composition  and  use     .         .         .     298 

Sect.  2.  Manures  consisting  of  animal  salts. 

1.  Urine  of  the  cow,  composition  and  value       ....  300 

2.  Urine  of  the  horse  "  "  ....  300 

3.  Human  urine  .........  300 

Sect.  3.  Manures  composed  mostly  of  geine. 

I.  Sea  weed. — 1.  Ribbon  weed.  2.  Carrageen  moss.  3.  Rock 
weed.  4.  Eel  grass.  5.  Sea  coral.  Preparation  and  applica- 
tion of  sea  weed      .........     303 

II.  Peat,  swamp  muck  and  pond  mud,  their  comparative  value     306 

1.  Peat  composted  with  alkalies 306 

2.  Peat  composted  with  animal  matter  ....     308 

3.  Peat  composted  with  green  manures  ....     309 

Sect.  4.  Methods  of  applying  manures. 
1.  For  cold  stiff  soils.     2.  For  light  sandy  soils      .         .         .     311 
3.  Action  of  green  manures  on  hoed  crops  and  grain  crops        311 

Sect.  5,  Saline  manures^  or  those  consisting  of  inorganic  salts. 

I.  Salts  whose  acid  contains  the  elements  which  nourish  plants   312 

1.  Nitrates,  theory  of  their  action 313 

2,  Phosphates.     3.  Carbonates,  theory  of  their  action            .  314 

Theory  of  the  action  of  lime 315 

Utility  of  lime  in  agriculture 317 

Action  of  ashes,  their  composition 317 

Peat  ashes,  leached  ashes,  white-ash 318 

II.  Salts  whose  acid  does  not  enter  into  the  composition  of 
plants,  and  whose  action  is  poisonous 319 


XVlll  CONTENTS. 

1.  Sulphate  of  lime,  utility  of  copperas           ....  319 

2.  Chlorites — common  salt,  spent  lye 319 

Rules  for  the  application  of  saline  manures       ....  320 

Sect.  6.  Improvement  of  the  soil  by  tillage. 

Utility  of  the  roller 322 

Utility  of  the  cultivator.     Importance  of  tillage          .         .         .  323 


CHAPTER  VIII. 

PRACTICAL  AGRICULTURE. 

Sect.  1.   Cultivation  of  grains. 

1.  Indian  corn .         .         .  324 

2.  Wheat,  mode  of  culture 327 

Diseases  and  enemies  of  u'heat. 

1.  Rust  described,  remedy  for 32S 

2.  Mildew  or  blight,  remedy  for 329 

3.  Smut— remedy 329 

4.  Wire-worm.     5.  Hessian  fly.     G.   Grain  insect          .         .  329 
Cultivation  of  rye — value  of  this  crop 330 

«              oats                "              331 

«               barley             "               332 

«              buckwheat    «              333 


Sect.  2. — Cultivation  of  roots. 
Potato — method  of  selecting  seed 
Beets — Mangel  Wurtzel.  Drill-barrow     . 

Turnip  and  blood-beet — value  of  the  crop 
Parsnip.     Artichoke.     Onion.     Turnips    . 
1.  Rutabaga — mode  of  culture,  value 


333 
335 
336 
337 

338 


2.   White  turnip.     3.  Yellow  turnip.           Table  of  Value         .  338 

Sect.  3.   Cultivation  of  grasses. 

1.  Clovers. — 1.  Red-top,  cultivation  of 341 

2.  Cow  grass  or  Southern  clover             342 

3.  White  clover.     4.  Lucerne  or  French  clover    .         .         .  343 

5,  Timothy 344 

6.  Red-top.     7.  Orchard  grass.    8.  Tall  oat  grass         .         .  345 
9.  Sweet-scented  vernal  grass.     10.  Rye  grass      .         .         .  346 

Relation  of  farm  stock  to  the  cultivated  crops. 


CONTENTS.  XIX 

CHAI^TER  IX. 

HORTICULTURE. 

Sect.  1.  Selection  of  seeds ^  propagation  and  improvement  of  races. 

I.  Maturation  of  seed 350 

Causes  of  sterility 350 

II.  Preservation  of  races  or  varieties 352 

III.  Improvement  of  varieties  and  races 354 

Sect.  2.  Propagaiion  by  eyes,  cuttings^  grafting  and  budding. 

I.  Propagation  by  eyes  and  buds 355 

II.  "                 cuttings  and  slips 355 

III.  "                 grafting  and  budding 356 

Operations  of  grafting. 

1.  Whip  grafting 357 

2.  Crown  grafting           ........  358 

3.  Saddle  grafting 358 

4.  Budding — illustration  of 359 

Sect.  3.  Pruning,  Training,  Potting  and  Transplanting. 

I.  Pruning — process,  use  and  effects  of 359 

II.  Training — process  and  use  of- 362 

III.  Potting — process,  conditions  of 363 

IV.  Transplanting— best  method 363 


ERRATA. 

Page    68 — (4)  instead  of  "  the  soil  "  read  "  the  seed." 
"       92 — 1.  4th  line,  for  "  appertures  "  read  "apertures." 
"     139 — margin,  for  "  Johnson  "  read  "  Johnston," 
"     149 — for  paragraph  "  6."  read  "7." 
"     159 — margin,  for  "  Johnson  "  read  "  Johnston." 
"     168 — 5th  paragraph,  for  " /syraorp/ttsm  "  read  ^'' Isomorphism.'* 
"     184 — 2.  2d  line,  for  "lamella"  and  "granula"  read  "lamel- 
lar "  and  "  granular." 
«     276— Hi.  7th  line,  for  "  De  Condolle  "  read  "  De  Candolle." 
"     277 — 2d  paragraph,    1st  line,    for   '^  Macaire  Princeps  "    read 

"  Macaire  Princep." 
"     296 — C.  1st  line,  leave  out  the  words  '^  jelly,  etc." 
"     303 — 2.  1st  line,   for   '^  Curagreen  moss"     read    '•'■  Carrageen 


INTRODUCTION. 


Agriculture  is  the  art  of  cultivating  the  soil.  It  includes 
aJl  those  processes  which  are  requisite  for  the  cultivation  of 
the  various  grasses,  graihs  and  fruits.  The  rearing  and 
fattening  of  animals,  and  the  preservation  and  use  of  their 
productions,  are  generally  connected  with  it. 

Agriculture  may  also  be  regarded  as  a  science;  in  which 
sense,  it  explains  the  reasons  for  these  processes,  or  gives 
rules  derived  from  experience  for  the  performance  of  each 
operation  of  the  art.  As  a  science,  it  is  of  recent  date,  and 
like  all  new  sciences  many  of  its  principles  are  not  yet 'fully 
settled.  As  an  art,  it  is  the  oldest,  the  mother  of  all  other 
arts,  having  been  practised  by  the  first  parents  and  founders 
of  the  race. 

Agriculture  must  be  regarded  as  the  most  important  art 
whether  we  take  into  view  the  number  of  men  it  has  always 
employed,  the  quantity  and  value  of  its  productions  or  the 
character  of  the  influence  which  it  exerts  upon  society. 

The  majority  of  men  are  farmers,  and  farmers  constitute 
the  bone  and  sinew  of  the  state.  But  if  we  take  simply  the 
quantity  and  value  of  the  agricultural  productions,  we  shall 
find  that  agriculture  is  the  greatest  pecuniary  interest  of 
every  country. 

In  England  and  Wales,  according  toMcCulloch,  the  quan- 
tity of  wheat  is  not  less  than   12,350,000  quarters,  worth 
31,000,000/.  sterling;  of  oats  and  beans,  13,500,000  quarters 
worth  17,500,000/.  sterlmg ;   to  which  may  be  added  the 
value  of  the  grass  lands,  worth  60,000,000/.  sterling. 

According  to  the  agricultural  returns  for  1839,  the  quan- 


18  ♦introduction. 

tity  of  wheat  in  the  United  States  is  91,642,957  bushels  an- 
nually, worth,  at  one  dollar  per  bushel,  $91,642,957;  of 
other  grains,  oats,  rye,  corn,  etc.  550,299,557  bushels,  worth 
upon  an  average  at  least  fifty  cents  per  bushel,  which  would 
amount  to  S275, 149,778 ;  of  potatoes,  113,183,619  bushels, 
worth,  at  twenty  cents  per  bushel,  $^22,6^.6,'/ 23,  giving  a  to- 
tal value  of  cultivated  crops  of  8389,429,459.  But  this  is 
but  a  small  part  of  all  the  productions.  The  whole  agricul- 
tural produce  of  the  country,  including  the  domestic  animals, 
must  be  worth  more  than  twice  this  amount.  A  late  writer 
has  estimated  the  total  value  of  the  products  of  the  country 
including  manufiictures,  at  1200  millions  of  dollars  annually; 
the  manufactured  products  being  less  than  200  millions. 
''  There  is  no  profession,"  says  Liebig,  "  which  can  be  com- 
pared in  importance  with  that  of  agriculture,  for  to  it  belongs 
the  production  of  food  for  man  and  animals ;  on  it  depends 
the  welfare  and  development  of  the  whole  human  species, 
the  riches  of  states  and  all  commerce.  There  is  no  other 
profession,  in  which  the  application  of  correct  principles  is 
productive  of  more  beneficial  effects,  or  is  of  greater  and  more 
decided  influence."  Compared  then  with  this  interest,  all 
others  are  of  minor  importance. 

Such  is  the  incalculable  interest  involved  in  the  art,  that  it 
becomes  a  question  of  primary  importance,  what  aid  it  may 
derive  from  the  physical  sciences. 

It  can  be  shown  I  think,  in  very  few  words,  that  botany, 
chemistry,  mineralogy  and  geology,  furnish  us  with  many 
principles  which  may  be  applied  to  this  art  to  render  it  more 
perfect,  and  more  productive.  The  laws  of  nature  are  con- 
stant and  unchanging  in  their  action.  If  we  can  learn  what 
these  laws  are,  as  they  stand  related  to  the  vegetable  kingdom, 
we  may  receive  important  aid  from  being  able  to  control 
them,  or  to  bring  our  efforts  to  coincide  with  their  agency. 

I.  Mineralogy  and  Geolo(jy  afford  aid  to  agriculture 
chiefly  by  enabling  us  to  determine,  by  the  inspection  of  the 


INTRODUCTION.    .  19 

rocks  and  simple  minerals,  the  character  of  the  soil.  As  all 
soils  originate  from  the  decay  of  rocks,  if  we  know  what  rocks 
are  crumbled  into  soil  we  may  determine  with  some  degree 
of  probability  its  character,  and  what  agencies  are  at  work  to 
benefit  or  injure  the  expected  crop.  If  by  a  simple  inspection 
of  the  mineral  ingredients  of  a  soil,  we  may  determine  what 
crop  will  best  flourish  upon  it,  we  certainly  must  regard  the 
aid  not  only  seasonable,  by  preventing  us  from  expensive  ex- 
periments, but  also  highly  valuable,  by  enabling  us  to  obtain 
a  greater  quantity  of  productions.  So  great  is  the  aid  which 
geology  renders  to  agriculture,  that  one  branch  of  it,  the  origin 
and  descriptions  of  soils,  is  called  by  one  writer  (Hitchcock), 
"Agricultural  Geology."  Geology  further  aids  agriculture 
by  pointing  out  the  location  of  useful  manures,  such  as  veg- 
getable  matters,  lime  and  plaster. 

II.  Chemistry  offers  greater  aid  by  far,  to  agriculture 
than  any  other  science,  because  it  explains  those  changes 
which  must  take  place  in  the  vegetable  organs,  and  in  the 
soil,  by  which  the  processes  of  vegetation  are  carried  forward  ; 
that  is,  chemistry  supplies  the  greater  number  of  the  condi- 
tions and  agencies  which  are  requisite  to  the  highest  activity 
of  the  vital  functions  of  plants,  and  hence  teaches  us  how  to 
obtain,  with  the  least  expense,  both  the  largest  quantity,  and 
the  best  quality,  of  products.  So  great  is  its  importance, 
and  so  far  does  it  exceed  all  other  branches  of  knowledge,  in 
its  relation  to  agriculture,  that  the  terms  ''  Agricultural 
Chemistry"  (Davy),  "  Chemistry  of  Agriculture"  (Liebig), 
"Chemistry  applied  to  Agriculture"  (Chaptal),  have  been 
employed  as  titles  of  the  most  important  works,  in  which  at- 
tempts have  been  made  to  apply  the  principles  of  science  to 
this  art. 

It  may  be  necessary,  however,  to  point  out,  in  a  general 
way,  some  of  the  specific  forms  in  which  this  science  may  be 
useful  to  agriculture,  both  for  the  sake  of  illustrating  the  gen- 
eral nature  of  the  subject,  and  its  importance  to  the  farmer.     • 


20 


INTRODUCTION. 


The  influence  which  chemistry  exerts  may  be  seen  by  means 
of  the  chemical  forces  which  are  acting  both  upon  dead  and  liv- 
ing matter.  The  principal  agents,  by  which  chemistry  produ- 
ces its  beneficial  results,  are  affinity,  heat,  light  and  electricity. 

1.  Chemical  Affinity.  This  is  the  great  agent  or  cause  of 
all  chemical  changes  on  the  surface  of  the  earth.  It  is  an  at- 
traction which  one  kind  of  matter  has  for  matter  of  an  oppo- 
site kind.  In  this  respect,  it  differs  from  cohesion  which  acts 
between  matter  of  the  same  kind,  as  between  two  smooth  pie- 
ces of  lead,  and  it  differs  from  gravitation,  which  cnly  acts  upon 
matter  in  masses,  while  affinity  effects  changes  within  imper- 
ceptible distances.  It  tends  to  draw  together  different  kinds 
of  matter,  and  to  continue  the  compound  until  some  force  acts 
upon  it  to  produce  decomposition.  This  force  may  be  heat, 
light  or  electricity,  but  generally  it  is  affinity  itself ;  for  the 
most  important  law  of  its  action  is,  that  one  kind  of  matter 
does  not  manifest  the  same  desire  to  unite  with  every  other  kind 
indiscriminately,  but  the  force  of  affinity  is  different  between 
different  bodies  ;  so  that  when  two  simple  bodies  are  unhed 
by  its  force,  some  third  body  may  have  a  stronger  attraction 
for  each  of  the  constituents,  or  for  one  of  them,  than  they  have 
for  each  other,  and  the  consequence  will  be  that  the  compound 
will  be  decomposed  ;  the  third  body  will  unite  with  one  con- 
stituent of  the  compound,  and  form  a  new  and  different  sub- 
stance. Thus,  for  example,  the  well  known  substance  ro/> 
peras,  is  found  in  some  soils  ;  it  is  composed  of  sulphuric  acid 
(oil  of  vitriol) ,  and  oxide  of  iron  (iron  7mbt),  and  these  two 
bodies  are  held  together  by  the  force  of  affinity ;  but  when 
carbonate  of  lime,  common  limestone,  is  scattered  over  such  a 
soil  the  copperas  is  decomposed,  the  sulphuric  acid  leaves  the 
oxide  of  iron,  being  drawn  away  by  its  stronger  affinity  for 
lime,  and  sulphate  of  lime  is  formed,  which  is  commonly 
called  gypsum  or  plaster  of  Paris. 

In  consequence  of  this  election  of  one  body  in  preference 
,^    to  another,  the  composition  and  decomposition  of  bodies  are 


INTRODUCTION.  21 

rapidly  effected.  In  some  cases  two  compounds  are  mutually 
decomposed,  and  two  new  compounds  formed ;  hence,  as  the 
force  of  these  affinities  is  well  known,  we  may  calculate  their 
influence  in  the  soil,  and  to  some  extent  in  the  organs  of 
plants.  We  have  only  to  ascertain  of  what  the  soil  is  compo- 
sed, to  know  what  changes  are  going  forward  in  it,  and  what 
decompositions  and  recompositions  will  take  place,  when 
we  add  earths,  salts  and  manures  to  it ;  and  hence  we  are 
furnished  with  the  means  of  producing  any  effect  that  we 
wish,  and  of  securing  the  action  of  the  proper  agents  upon 
the  expected  crop. 

But  to  show  further  the  agency  of  affinity,  it  will  be  neces- 
sary to  notice  some  of  the  laws  which  govern  it,  and  the  other 
agents  which  modify  its  action. 

When  bodies  combine  by  the  force  of  affinity,  they  do 
not  generally  unite  in  any  and  every  quantity  or  proportion, 
but  are  governed  by  strict  laws,  that  is,  definite  quantities  of 
each  are  required  to  complete  their  union  ;  thus  water  is 
formed  by  the  union  of  1  part  by  weight  of  hydrogen  and 
8  parts  of  oxygen ;  so  carbonic  acid  (or  Jized  air)  is  composed 
of  exactly  6.12  parts  by  weight  of  carbon  and  16  parts  of  oxy- 
gen, and  if  the  proportions  of  these  substances  are  changed, 
some  other  substances  will  be  formed,  but  neither  water  nor 
carbonic  acid.  Similar  laws  are  observed  when  bodies  com- 
bine by  volume  or  measure,  and  these  laws  extend  to  the 
greater  number  of  compounds  both  organic  and  inorganic ; 
hence,  as  these  quantities  are  all  determined  (the  smallest  in 
which  any  body  combines  being  called  its  equivalent  or  pro- 
portional), we  may  not  only  explain  changes  in  the  process 
of  vegetation,  and  deduce  important  laws  which  tend  to  satis- 
fy the  mind  in  its  investigations,  but,  in  a  more  practical  way, 
we  can  determine  the  quantities  of  different  substances  which 
any  particular  soil  may  require,  especially  when  one  saline 
compound  is  substituted  for  another.  Thus,  for  example, 
when  salts  of  ammonia  are  applied  to  the  soil  for  the  purpose 
2* 


32  INTRODUCTION. 

of  obtaining  the  influence  of  the  ammonia,  100  lbs.  of  the  car- 
bonate yields  an  amount  of  ammonia  equal  to  146  lbs.  of  the 
sulphate.  This  result  has  been  found  out  by  long  experience, 
but  a  knowledge  of  chemical  proportions  would  have  pre- 
dicted it. 

When  substances  thus  combine  in  definite  proportions, 
the  compounds,  generally,  bear  no  analogy  to  either  of  the 
constituents.  The  new  substances  formed  are  in  the  posses- 
sion of  properties  entirely  new,  and  which  could  not  have 
been  predicted  previous  to  experiment ;  hence  two  simple 
bodies  by  combining  in  different  proportions  form  entirely 
different  and  distinct  bodies,  as  different  as  common  air, 
the  exhilarating  gas,  and  nitric  acid  (aquafortis),  which  are 
compounds  of  oxygen  and  nitrogen ;  hence  it  is,  that  the  al- 
most infinite  variety  of  vegetable  productions  are  formed  by 
the  different  combinations  of  a  few  simple  substances.  If, 
therefore,  we  wish  to  produce  a  greater  quantity  of  any 
given  production,  we  must  supply  the  conditions  which  will 
cause  such  combinations  to  take  place.  Thus,  for  example, 
where  soils  are  destitute  of  animal  manures,  from  which  the 
nitrogen  may  be  procured  necessary  to  form  gluten  and  vege- 
table albumen  in  wheat,  an  addition  of  nitrate  of  potash,  soda 
or  ammonia,  will  increase  the  amount  of  these  substances,  and 
render  the  grain  much  more  valuable ;  an  addition  of  2^  per 
cent,  of  gluten  has  been  thus  produced  in  the  same  weight  of 
wheat,  which  would  add  more  than  10  per  cent,  to  its  value. 

In  consequence  of  the  fact,  that  each  substance  has  a 
definite  and  fixed  character,  we  are  enabled,  by  the  aid  of 
afl[inity,  to  decompose  soils,  and  to  compare  with  them  the 
vegetable  products ;  hence  we  can  not  only  learn  the  rea- 
son of  fertility  or  barrenness,  but  also  how  to  remedy  de- 
fects, and  thus  point  out  to  the  practical  agriculturist  the  pro- 
cess which  will  secure  a  bountiful  crop.  If  an  analysis  of 
the  soil  be  made  before  and  after  the  crop,  we  may  determine 
what  the  effect  of  any  substance  is  upon  it.     By  the  aid  of 


INTRODUCTION. 


affinity  we  may  also  analyze  the  vegetable  productions,  and 
learn  what  ingredients  each  species  of  plant  requires  for  its 
most  perfect  growth. 

The  quality  of  the  productions  themselves  is  also  indicated 
in  these  processes,  for  it  is  found  that  the  same  quantities  of 
wheat  will  not  always  make  the  same  quantity  of  bread.  The 
conditions  therefore  on  which  these  differences  depend,  we 
may  learn  from  an  accurate  knowledge,  and  application  of 
chemical  principles. 

Another  point,  of  great  interest  to  the  agriculturist,  is  the 
theory  of  the  action  of  manures,  and  it  is  to  chemistry 
that  he  must  look  for  the  most  important  histructions  on  this 
subject.  A  knowledge  of  the  action  of  saline  compounds, 
and  of  alkalies,  is  all-important  to  the  farmer.  A  continued 
course  of  cropping  removes  them  from  the  soil,  and  the  cheap- 
est and  most  effectual  means  of  restoring  them  is  a  matter  of  the 
first  necessity  to  a  perfect  system  of  tillage. 

And  finally,  "  the  source  of  the  failure  of  crops  when  plant- 
ed on  the  same  soil  for  several  successive  years,"  is  a  subject 
to  be  investigated,  and  its  facts  explained  by  chemical  prin- 
ciples. This  will  afford  an  explanation  of  rotation  of  crops, 
and  point  out  many  important  practical  rules  in  regard  to  this 
subject. 

In  these,  and  numerous  other  ways,  which  we  have  not  time 
to  specify,  chemistry  may  afford  important  aid  to  agriculture. 
The  other  chemical  forces,  such  as  heat,  light  and  electricity, 
not  only  modify  the  action  of  affinity,  but  act  directly  upon 
the  vital  functions  of  plants. 

2.  Caloric  or  Heat  exerts  an  agency  scarcely  less  impor- 
tant than  affinity  itself.  It  also  acts  according  to  fixed 
laws,  which  are  known.  The  application  of  these  laws  to 
agriculture,  still  further  illustrates  the  utility  of  chemical  sci- 
ence, and  is  too  obvious  to  need  further  specification  in  this 
connection. 

3.  Light  is  absolutely  essential  to  vegetation,  but  its  influ- 


24  INTRODUCTION. 

ence  is  not  so  immediately  under  the  control  of  the  agricul- 
turist as  any  of  the  preceding  agents. 

4.  Elcctricitij  even  more  readily  yields  its  agency  to  the 
skill  of  man.  The  electrical  character  of  the  soil  may  readily 
be  determined.  It  may  even  be  changed  by  artificial  appli- 
ances, and  hence  what  was  barren  and  worthless,  may  be 
rendered  fruitful.  But  as  these  latter  forces  will  receive  par- 
ticular attention,  as  to  their  influence  on  vegetation,  in  the 
body  of  this  work,  it  is  unnecessary  to  enter  into  any  further 
specification  of  their  agency. 

The  chemical  forces  above  enumerated,  in  their  influence 
upon  vegetables  themselves,  are  in  subordination  to  another 
force,  the  living  power  ;  and  hence  we  must  resort  to 
vegetable  physiology  {or  further  aid,  in  explaining  the  pro- 
cesses of  vegetation,  and  in  pointing  out  the  conditions  for 
successful  practice  in  agriculture. 

III.  Botany  furnishes  us  with  principles  more  directly  ap- 
plicable to  agriculture,  as  a  science,  than  either  of  the  preced- 
ing sciences.  In  fact,  one  branch  of  this  science,  the  living 
functions  of  plants,  or  Biology,  including  the  conditions  of 
life,  and  all  the  near  or  remote  influences  which  act  upon  the 
vital  forces,  and  tend  to  quicken  or  destroy  them,  constitutes 
of  itself  the  whole  science  of  agriculture.  Such  a  view,  how- 
ever, might  properly  bring  in  chemistry,  as  a  modifying  force, 
as  well  as  mineralogy  and  geology.  In  a  more  restricted 
sense,  botany  offers  the  following  aids : 

1.  It  explains  the  structure  of  the  various  organs  of  plants, 
by  which  we  are  made  acquainted  with  the  means  of  introduc- 
ing and  disposing  of  the  matter  by  which  they  are  nourished. 

3.  It  determines  the  habits  of  each  species  of  plant,  by 
which  we  are  enabled  to  adapt  the  crop  to  the  climate  and  soil. 

3.  It  points  out  what  plants  require  as  the  condition  of 
their  most  perfect  growth,  and  how  to  obtain  the  best  quality 
of  their  products.  It  enables  us  also  to  obtain  the  best  kinds 
or  species  of  plants,  to  ascertain  their  mode  of  propagation. 


INTRODUCTION.  25 

their  preservation  and  use,   with  the  diseases  which  attack 
them. 

Plan  of  the   Work. 

I.  In  accordance  with  the  above  views,  the  first  three 
chapters  are  devoted  to  the  conditions  of  the  life  of  plants,  un- 
der the  general  head  o^  Biology,  including  all  the  agents  that 
influence  the  processes  of  vegetation,  the  character,  composi- 
tion, source  and  assimilation  of  the  vegetable  principles. 

II.  The  next  four  chapters  are  devoted  to  the  composition 
of  the  rocks  ;  origin  and  classification,  composition  and  im- 
provement of  soils;  with  the  theories  of  the  action  of  ma- 
nures, rotation  of  crops,  fallow  crops,  and  practical  sugges- 
tions. 

III.  The  closing  chapter  explains  the  processes  of  Horticul- 
ture, with  the  application  of  those  principles  which  are  par- 
ticularly connected  with  this  important  branch  of  agriculture. 

The  object  of  the  work,  then,  generally,  is  to  explain  the 
phenomena  of  vegetation,  and  to  deduce  practical  rules  for 
the  benefit  of  the  practical  farmer ;  in  order  to  render  the 
modes  of  tillage  more  precise  and  rational,  and  thus  to  afford 
a  stimulus  to  intellectual  and  moral  improvement,  by  making 
farmers  more  scientific  men  ;  and  in  order  to  increase  the 
amount  of  agricultural  productions,  by  rendering  the  earth 
more  fertile,  and  the  processes  of  cultivation  easier  and  more 
successful. 

If  by  the  application  of  the  principles  contained  in  this 
work,  these  results  are  attained,  in  but  a  slight  degree,  it  is 
all  that  I  can  hope.  I  will  therefore  conclude  these  intro- 
ductory observations  by  a  calculation  of  the  value  of  any 
slight  improvement  in  this  most  useful  art. 

In  England,  "  the  average  produce  of  wheat,"  says  Mr.  Pu- 
sey,  "  is  stated  at  26  bushels  per  acre ;  if  by  a  better  selection 
of  seed  we  could  raise  this  amount  to  27  bushels  only,  (a  sup- 
position by  no  means  unlikely),  we  should  by  this  apparently 


26  INTRODUCTION. 

small  improvement  have  added  to  the  nation's  annual  income 
475,000  quarters  of  wheat,  worth,  at  fifty  shillings,  about 
1,200,000/.  yearly,  which  would  be  equal  to  a  capital  of  24, 
000,000/.  sterling  gained  forever  to  the  country  by  this  trifling 
increase  in  the  growth  of  one  article,  and  that  in  England  and 
Wales  alone;"  a  quantity  sufficient,  we  may  add,  to  feed  all 
her  starving  millions  in  the  manufacturing  districts  ;  and  if, 
by  any  means,  a  similar  increase  could  be  effected  in  her  other 
productions,  she  would  be  able  to  banish  forever  all  fear  of 
want,  which  now  so  frequently  threatens  to  undermine  the 
pillars  of  the  throne  itsdf. 

But  while  the  soil  of  England  has  reached  nearly  the  maxi- 
mum of  fertility,  ours  in  this  country  has  not.  Let  us  then  cal- 
culate the  value  of  some  slight  improvanmts  at  home,  which 
with  the  aid  of  science  and  skill,  may  easily  be  made,  in  a  few 
years,  with  little  or  no  expense  to  the  country. 

1.  Take  our  wheat  crop  for  1839.  As  the  number  of 
acres  is  not  given,  we  cannot  decide  with  perfect  accuracy 
the  average  per  acre  ;  but  taking  the  estimate  made  for  the 
state  of  Massachusetts  the  same  year,  the  quantity  is  about 
15  bushels  per  acre.  The  Middle  and  Western  States  yield 
a  much  larger  quantity,  I  think  therefore  we  may  be  safe  in 
estimating  the  average  at  20  bushels  per  acre.  Then  91, 
642,957  bushels  annually  produced,  would  require  the  culti- 
vation of  4,582,147  acres  of  land.  Suppose  now  that  by  the 
use  of  improved  modes  of  culture,  selection  of  seeds,  etc.  we 
could  make  our  wheat  lands  produce,  on  an  average,  as  much 
as  those  of  England,  26  bushels  instead  of  20  to  the  acre,  (and 
this  certainly  might  be  done),  this  increase  would  amount 
annually  to  27,492,882  bushels.  This  would  add  as  many 
dollars  to  the  national  income,  and  would  be  equal  to  an  in- 
vestment of  458,214,700  dollars! 

2.  Let  us  apply  the  same  calculation  to  corn,  rye,  oats,  etc. 
and  as  387  millions  of  bushels  are  corn,  we  may  estimate 
these  products,  upon  an  average,  at  30  bushels  to  the  acre* 


INTRODUCTION.  27 

There  would  then  be  18,343,318  acres  devoted  to  these  crops. 
Suppose  now  by  the  application  of  scientific  principles  the 
same  increase  per  acre  might  be  effected,  viz.  36  bushels  in- 
stead of  30,  there  would  be  added  to  the  quantity  now  ob- 
tained 110,059,908  bushels  ;  and  if  we  estimate  the  whole  at 
50  cents  per  bushel,  it  would  add  55,029,954  dollars  to  the 
annual  income  of  the  country,  equal  to  an  invested  capital  of 
917,165,900  dollars! 

3.  Apply  the  same  calculations  to  the  potato  crop  ;  and 
taking  the  crop  in  Massachusetts  of  1839  for  the  average,  at 
200  bushels  per  acre,  the  113,183,619  bushels  raised  in 
this  country  in  1839  would  require  565,918  acres  of  land. 
Suppose  now  an  increase  of  25  bushels  per  acre,  (an  estimate 
far  below  what  might  l^e  realized,)  and  there  would  be  added 
to  the  present  quantity  of  this  crop,  14,647,950  bushels; 
which,  at  20  cents  per  bushel,  would  amount  to  2,929,590 
dollars,  equivalent  to  a  capital  of  48,826,500  dollars  ! 

4.  If  now  we  estimate  the  total  income  to  the  national 
wealth,  by  this  addition  to  the  cultivated  crops,  it  will  amount 
to  the  sum  of  85,4.52,526  dollars,  equivalent  to  a  capital  of 
1,424,207,100  dollars!  But  this  sum  is  derived  from  but  a 
few  of  the  products  of  the  soil.  When  we  take  into  account 
the  hay  and  other  agricultural  productions,  and  allow  the 
same  relative  increase,  the  amount  would  be  more  than 
doubled.  Thus  a  sum  of  money  might  easily  be  realized 
which  would  be  sufficient  to  found  all  the  colleges  and  institu- 
tions of  learning,  build  all  the  rail-roads  and  canals,  which  the 
wants  of  the  country  might  demand  during  all  coming  time  ! 

Let  us  now  confine  our  estimates  to  a  narrower  sphere. 
"  Suppose  that  the  agricultural  survey,"  says  Mr.  Colman, 
in  his  Fourth  Report  of  the  Agriculture  of  Massachusetts, 
"  may  have  been,  or  may  have  proved  instrumental  in  induc- 
ing, upon  an  average,  by  improved  cultivation,  an  increase  of 
one  hundred  bushels  of  corn  to  every  town  in  the  Common- 
wealth ;  this,  at   seventy-five  cents  per  bushel  for  corn,  and 


28  INTRODUCTION. 

ten  dollars  per  ton  for  corn  fodder,  would  be  upwards  of 
28,000  dollars.  Suppose  it  may  conduce  to  the  production 
of  an  average  of  one  hundred  tons  of  compost  manure 
in  each  town  in  the  Commonwealth,  which  must  be  valued 
at  one  dollar  per  load  ;  this  would  exceed  a  yearly  income  of 
60,000  dollars,  to  say  nothing  of  the  permanent  improvement 
it  would  effect  in  the  soil.  Suppose  that  it  may  conduce  to 
the  redemption  of  1000  acres  of  peat  bog,  which  is  now  worth- 
less, converting  it  into  productive  meadows  yielding  two 
tons  of  hay  to  the  acre,  and  keeping  up  its  condition ;  this 
would  be  little  more  than  three  acres  to  a  town  ;  and  rating 
its  value  by  its  income  (it  cannot  be  estimated  at  less  than 
150  dollars  per  acre)  this  would  be  an  increase  of  the  pro- 
perty of  the  State,  which  may  be  safely  called  an  actual  crea- 
tion of  land,  to  the  value  of  150,000  dollars,  and  a  permanent 
income  of  more  than  20,000  dollars  per  year.  Here  is  no 
extravagant  calculation,  to  say  nothing  of  many  other  forms 
in  which  the  influence  of  the  survey  may  be  felt." 

Finally,  in  order  to  obtain  just  views  of  this  subject,  it  must 
be  remembered,  that  the  above  improvements  imply  a  very 
great  intellectual  and  moral  advancement  in  the  agricultural 
community  ;  an  elevation  of  the  popular  mind,  the  value  of 
which  cannot  be  estimated  by  bushels  of  grain,  by  silver  and 
gold  coin,  but  by  the  purity,  stability  and  extension  of  our 
social,  civil  and  religious  institutions ;  and  by  the  increased 
facilities  for  cultivating  the  higher  powers  of  man.  The  in- 
crease of  national  wealth  is  a  desirable  and  laudable  object 
of  pursuit,  but  it  is  mainly  from  the  intellectual  and  moral 
influence  which  an  improved  agriculture  will  exert  upon  so- 
ciety, that  we  can  derive  an  adequate  idea  of  its  magnitude 
and  importance.  Imperfect  as  the  science  of  agriculture  now 
is,  and  imperfectly  as  it  is  represented  in  the  following  pages, 
the  interest  is  so  vast,  that  if  any  slight  improvement  is  secu- 
red, I  shall  not  deem  my  labor  wholly  lost. 


BIOLOGY   OF    PLANTS 


CHAPTER  L 

THE  VITAL  PRINCIPLE. 

Material  bodies  have  been  divided  into  three  kingdoms, 
animal,  vegetable  and  mineral.  This  division  is  an  obvious 
one,  and  is  a  convenient  mode  of  classifying  the  phenomena 
which  each  presents  to  the  view  of  the  common  observer. 

But  a  more  philosophical  examination  discloses  the  fact, 
that  animals  and  vegetables  have  many  points  of  analogy,  and 
that  they  both  differ  essentially,  from  minerals.  This  differ- 
ence is  manifested  in  various  ways,  in  the  mode  of  their  origin, 
their  food,  growth  and  dependance  upon  other  matter,  foreign 
to  themselves.  But  all  these  different  modes  of  existence 
may  be  traced  to  a  peculiar  power,  which  has  been  called  the 
vital  principle ;  hence  a  more  philosophical  division  of  natural 
objects,  is  into  those  which  arepossessed  of  life,  and  those  which 
are  destitute  of  it.  The  former  have  been  called  organic, 
and  the  latter  inorganic  bodies. 

Sect.  1.  Defnitions. — Proofs,  Nature  and  Uses  of  the  Vital 
Principle. 

1.  Biology  is  the  science  of  life.  The  term  is  derived  from 
two  Greek  words,  and  is  similar  in  signification  to  the  term 
Physiology.  It  includes  all  the  agencies  and  conditions  which 
are  essential  to  the  existence  and  reproduction  of  living  beings. 
The  term  Biology  of  plants  signifies  nearly  the  same  as  vegeta- 
ble physiology.  It  includes  that  peculiar  power  which  has  been 
called  the  "  vital  principle,''^  and  its  connection  with  those  agen- 
3 


30 


BIOLOGY  OF  PLANTS. 


cies  which  in  any  way  act  upon  it,  or  seem  necessary  to  its  de- 
velo|)tnent  in  the  processes  of  vegetation,  such  as  soil,  food,  air, 
water,  gravity,  affinity,  heat,  light,  electricity  and  the  agency  of 
man. 

2.  "  An  organized  body  is  one  in  which  all  the  parts  are  mu- 
tually means  and  ends,"*  that  is,  "  each  portion  ministers  to  the 
others,  and  each  depends  upon  the  other,"  the  parts  make  up  the 
whole,  but  the  existence  of  the  whole  is  essential  to  the  pre- 
servation of  the  parts.  The  parts  are  organs,  and  the  ichole  is 
organized.^'' 
»  "  We  conceive  animal  life  as  a  vortex,  or  cycle  of  moving  matter, 
in  which  the  form  of  the  vortex  determines  the  motions,  and 
these  motions  again  suj)iJort  the  form  of  the  vortex ;  the  station- 
aiy  parts  circulate  the  fluids,  and  the  fluids  nourish  the  perma- 
nent parts."t 

The  same  view  may  be  taken  of  plants.  In  some  vegetable 
products,  the  organs  appear  in  a  distinct  form,  as  in  the  wood, 
leaf  and  blossom.  In  other  products,  as  starch,  gum  and  sugar, 
no  such  marks  of  organization  can  be  distinguished.  All  orga- 
nized bodies  are  the  products  of  the  living  principle,  whether 
those  now  j)0ssessed  of  life,  or  those  that  have  been  possessed 
of  it,  or  those  which  have  been  derived  from  living  bodies,  as 
alcohol  and  vinegar. 

3.  A  plant  is  an  organized  and  living  substance,  springing 
from  a  seed  or  germ,  which  it  reproduces.  It  is  composed  of 
an  irritaole,  elastic  matter,  called  tissxie.  Tissue  is  of  two  kinds, 
the  cellular  analogous  to  the  flesh  and  soft  parts  of  animals,  and 
the  vascular,  which  is  similar  to  the  bones  of  animals. 

4.  All  plants  are  made  up  of  cells  or 
ve^sicks,  (Fig.  I,  a  a  a,)  of  different  forms, 
with  thin,  transijarent  walls.  When  these 
cells  press  against  each  other,  small  in- 
tervals are  lefl  between  them  which  al- 
so form  tubes,  called  intercellular  canals. 
They  are  the  vessels  in  which  the  sap 
is  carried  up  from  the  roots  to  the  leaves. 
When  these  intervals  increase  in  size, 
so  as  to  exceed  many  times  the  diame- 
ter of  the  cells,  they  are  called  the  pro- 
per vessels. 


Fiff 


Kant. 


t  Whewell. 


DEFINITIONS  AND  DESCRIPTIONS. 


31 


Fig.  3. 


5.  Cells  are  of  three  kinds. 
(1)  Those  of  the  bark  and  pith, 
of  an  elhpsoidal  form.  (2)  Elon- 
gated cells  of  tlie  liber  aiul  wood. 
Tliese  cells  constitute  the  in- 
terior of  the  hark,  and  are  the 
basis  of  wood])  fibre.  (3)  Cells 
of  the  medullarrj  rays.  The 
medullary  rays  pass  from  the 
pitii  to  the  bark  through  the 
wood,  as  in  Fig.  2.  c  m  m  m. 
These  cells  also  have  intercel- 
lular canals. 

6.  Spiral  vessels  exist  also  in  the  more  i)erfect  plants. 
They  are  called  spiral  because  they  are  fibres  twisted 
like  a  cork-screw,  (Fig.  3,)  around  an  empty  space. 
These  cells  occur  only  in  wood,  and  are  found  in  bun- 
dles. Each  bundle  contains  about  thirty  or  forty  spi- 
ral tubes.  A  new  bundle  is  formed  every  year,  con- 
stituting the  annual  layer  of  icood,  or  concentric  rings, 
as  in  Fig.  2.  They  are  supi)osed  to  be  air  vessels.  In 
grasses  and  grains  these  spiral  vessels  constitute  the 
part  around  the  interior  of  the  hollow  stem. 

7.  Pores  are  oblique  openings  or  slits  in  the  epider- 
mis or  cuticle,  so  small  tJiat  a  square  inch  of  the  e[)ider-    ''''^^:i:>^ 
mis  of  the  kidney   bean   contains  more  than  300,000       £^ 
pores.     These  pores  are  found  chieliy  on  the  under  side  of  the 
leaf,  and  are  the  organs  of  transpiration. 

8.  Epidermis  or  cuticle  is  a  very  thin 
membrane  which  envelopes  the  soft 
parts  of  plants,  as  the  leaves.  It  is 
sometimes  composed,  in  part,  of  silica. 

9.  Wood  is  formed  of  bundles  of 
spiral  tubes,  (See  Fig.  2,)  surrounded 
by  elongated  cells.  The  inner  hark, 
(Fig.  4.  1,)  is  called  the  liber,  and  in 
the  spring  a  mucilaginotis  matter  call- 
ed cambium  is  interposed  between  the 
liber  and  the  wood  ;  Irom  this  the 
first  soit  wood  is  formed,  called  albur- 
num, which  is  annually  attached  to 
the  tree,  while  a  thin  layer  is  formed 
on  the  liber  or  bark,  2,  3,  4,  5. 


32 


BIOLOGY  OF  PLANTS. 


In  Fig.  2,  c  represents  the  pith,  b  the  heart  wood,  a  the  al- 
burnum, II  m  the  bark.  The  annual  layers  of  wood,  the  medul- 
lary rays  and  the  tubes  are  also  represented  in  tliat  figure,  which 
is  a  representation  of  a  section  of  the  branch  of  a  tree. 

10.  The  process  of  converting  tlie  cambium  into  alburnum 
and  other  vegetable  substances,  such  as  sugar,  gum,  starch,  etc. 
is  called  assimilation  ;  that  of  rejecting  matter  by  the  roots,  ex- 
cretion and  by  the  leaves,  transpiration.  When  substances  are 
thrown  off  from  the  leaves,  they  are  also  said  to  be  exhaled ;  and 
when  they  are  taken  in  by  the  leaves,  they  are  said  to  be  inhaled 
or  absorbed. 

Agricultural  Chemistry  is  a  term  which  has  been  generally  used 
to  denote  the  ai)plication  of  science  to  Agriculture.  It  attempts 
to  explain  the  ijifluence  of  earth,  air  and  water  upon  plants. 

That  branch  of  the  subject,  which  relates  to  the  soil,  as  formed 
of  simple  minerals  and  rocks,  is  sometimes  called  Agricultural 
Geology.  But  as  the  chemical  and  geological  agents  are,  in  the 
processes  of  vegetation,  subjected  to  the  principle  of  life,  it  seems 
more  appropriate  to  include  the  vital  principle;  the  conditions 
of  its  action  ;  the  influence  of  other  agents  upon  it ;  its  produc- 
tions, with  their  composition  and  source,  under  the  term  Biol- 
ogy of  Plants  ;  while  the  subject  of  soils  and  manures  is  placed 
under  the  term  Geology  and  Chemistry  of  Soils. 

Plants  and  animals  differ  in  many  respects  from  each  other, 
as  in  their  structure,  in  the  nature  of  their  food  and  in  the 
mode  and  time  of  taking  and  digesting  it,  as  well  as  in  being 
governed  by  many  different  laws,  but  yet  they  both  agree  in 
possessing  a  living  principle.  This  power  is  probably  the 
same  in  both,  and  is  characterized  by  its  operations,  and  by 
its  pervading  every  part  of  organized  bodies.  Mechanical 
and  chemical  agents  are  subordinated  to  it,  in  the  living  sys- 
tem, and  would  be  wholly  inefl^cient  without  it. 

In  the  stomach  of  animals,  for  example,  this  power  is  the 
principal  agent  in  elaborating  the  juices  required  to  digest  the 
food.  It  enables  the  lacteal^  or  small  tubes  which  open  their 
mouths  into  the  alimentary  canal,  to  select,  from  the  general 
mass,  whatever  is  fitted  for  nourishment,  while  it  permits  what 
is  injurious  or  useless  to  pass  by.     It  sends  this  to  the  heart, 


THE  VITAL  PRINCIPLE.  33 

and  gives  it  its  never  ceasing  pulsations.  It  follows  the  blood 
to  the  lungs,  and  watches  over  the  changes  which  are  wrought 
there  by  the  atmosphere.  It  returns  with  the  blood  to  the 
heart,  and  propels  it  through  every  part  of  the  system,  where 
it  assimilates  it  to  the  living  body  ;  and  finally,  when  the  liv- 
ing flesh  and  bone  have  served  their  purpose  in  the  animal 
system,  and  the  matter  is  no  longer  fitted  to  give  strength  and 
life  to  the  part,  it  is  vitality  which  removes  it  to  make  room 
for  fresh  particles  which  this  same  power  has  prepared  to  fill 
the  place.  Thus  the  vital poicer  is  active  during  every  mo- 
ment of  animal  life,  in  converting  dead  into  living  matter, 
and  of  removing  it  when  it  is  no  longer  fitted  to  form  a  part 
of  the  living  system.  It  is  in  the  bones  and  muscles,  in  the 
tendons,  glands  and  skin ;  it  pervades  the  entire  body,  and 
presides  over  all  its  healthful  changes  and  operations. 

It  distinguishes  man  from  the  dust  on  which  he  treads.  By 
it  he  lives  and  moves ;  by  it  he  resists  the  laws  of  nature  which 
assail  him  on  every  side ;  by  it  he  wards  off  the  attacks  of 
disease,  or  expels  it  when  it  has  taken  possession  of  his  body ; 
by  it  he  clothes  himself  again  with  strength  and  beauty.  It  is 
this  vital  power  within,  that,  by  its  constant  and  all-pervading 
energy,  builds  up  and  keeps  in  action  that  wonderful  and  fear- 
ful tenement  which  is  his  earthly  habitation.  Nor  does  it 
cease  its  ever  active  agency  during  all  the' changes  and  acci- 
dents of  life,  until  his  spirit  departs  for  another  world. 

The  vital  principle  exerts  a  similar  influence,  though  not 
to  the  same  extent,  upon  vegetables.  It  is  this  power  which 
enables  the  roots  to  derive*  nourishment  from  the  soil,  and  the 
leaves  from  the  air.  It  aids  in  carrying  up  the  sap  through 
small  tubes  to  the  leaves,  where  a  change  is  wrought  upon  it 
by  contact  with  the  atmosphere.     It  sends  the  prepared  nu- 

*  The  powers  of  absorption  and  circulation  of  the  sap^  to  a  certain 
extent,  is  clue  to  chemical  and  mechanical  laws,  but  it  is  doubtful 
whether  the  phenomena  can  be  w^holly  explained  without  the  aid  of 
this  peculiar  power. 

3* 


34  BIOLOGY  OF  PLANTS. 

triment  down  between  the  bark  and  wood,  (in  perennial 
plants,)  and  assimilates  what  is  nutritious  to  the  livincr  tree; 
and,  although  most  of  the  matter  remains,  still  there  is  a  quan- 
tity taken  in  which  is  excreted  by  the  roots,  or  transpired 
through  the  leaves  as  unfit  to  enter  into  its  composition. 

This  power  exists  in  the  roots,  stem,  leaves,  juices,  flowers 
and  fruit,  and  presides  over  all  the  changes  which  are  carried 
forward  in  the  vegetable  economy.  In  this  case  also  many 
of  the  processes  are,  in  part,  purely  chemical  or  mechanical ; 
but  these  forces  would  be  of  no  avail  to  form  the  vegdable 
products,  if  the  living  power  or  vital  energy  were  absent,  and 
hence  we  may  ascribe  the  effect  to  that  power,  just  as  we  do 
chemical  changes  to  affinity,  although  many  other  agents  may 
operate  in  unison  with  it,  and  modify  its  action. 

As  some  chemists  are  disposed  to  doubt  the  existence  of 
such  a  power,  attempting  to  explain  the  phenomena  of  vege- 
tation by  chemical  and  mechanical  forces,  and  particularly 
by  what  are  denominated  "  chemical  transformations,"  I  will 
proceed  to  the 

Proofs  of  its  existence.  The  existence  of  such  a  power  in 
plants  and  animals  is  susceptible  of  the  same  kind  of  proof  as 
the  power  of  gravitation  or  attraction  in  general.  We  cannot 
subject  it  to  the  test  of  the  senses,  as  we  can  caloric,  light  and 
electricity.  We  infer  its  existence  from  the  effects  which  are 
produced,  and  which  cannot  be  shown  to  be  caused  by  those 
agents  which  are  capable  of  sensible  demonstration. 

That  such  a  power  exists  in  animals  might  be  easily  shown. 
But  it  is  more  important  for  our  purpose  to  exhibit  evidence 
of  its  existence  in  plants ;  in  which  this  force  differs  in  its 
operations,  in  the  conditions  requisite  for  its  development,  and 
in  the  instruments,  by  which  its  existence  is  continued. 

I.  Vegetables  j^ossess  the  poioer  of  resisting  or  counteracting 
the  laws  of  affinity,  gravity,  heat  and  cold. 

1.  The  process  of  the  absorption  of  food,  and  its  elabora- 
tion and  assimilation,  takes  place  in  opposition  to  the  laws  of 


PROOFS  OF  VITALITY.  35 

chemical  affinity ;  for  as  soon  as  the  plant  dies,  this  agent  be- 
gins to  exert  its  power.  The  elaborated  juices,  no  longer  pre- 
served by  the  vital  principle,  exert  their  mutual  affinities,  and 
the  whole  plant  in  time  is  resolved  into  its  original  elements. 
This  power  of  resisting  ordinary  chemical  laws,  and  of  con- 
trolling them  in  such  a  way  as  to  make  them  subservient  to 
nutrition,  evinces  a  peculiar  vital  energy, 

2.  Gravity  is  constantly  tending  to  bring  the  plant  and  its 
juices  to  the  earth  ;  but  in  opposition  to  this  power  the  sap 
ascends,  and  the  plant  or  tree  attains  in  some  cases  an  eleva- 
tion of  more  than  one  hundred  feet  from  the  surface  of  the 
ground.  A  part  of  the  matter  which  composes  the  tree  is  thus 
carried  up  in  opposition  to  gravity.  It  is  true  that  it  is  car- 
ried up  slowly,  and  in  small  capillary  tubes,  in  which  mechan- 
ical laws  operate  to  some  extent,  still  this  will  not  wholly  ac- 
count for  the  fact.     It  requires  vitality  to  effect  its  ascent. 

3.  Heat  and  cold,  two  powerful  agents  of  unorganized  bo- 
dies, are  resisted  by  vegetables  within  certain  limits.  The 
temperature  of  the  juices  of  plants,  and  of  their  solid  parts, 
does  not  rise  or  fall  with  that  of  the  surrounding  medium. 
The  living  vegetable  will  continue  to  flourish  at  a  temperature 
sufficiently  high  to  produce  disorganization  after  it  is  dead, 
while  the  juices  are  said  to  circulate  slowly  during  the  cold 
of  winter  ;  for  although  the  temperature  of  the  juices  is  far  be- 
low the  freezing  point,  they  do  not  always  congeal  unless  they 
are  taken  from  the  tree. 

This  power  of  resisting  the  extremes  of  heat  and  cold  is 
very  striking  in  the  case  of  some  animals,  which,  when  exposed 
to  a  temperature  of  300°  F;  or  to  — 80°  F.  retain  constantly  a 
temperature  at  9S  or  100°  F.  Vegetables  possess  this  proper- 
ty in  a  less  degree,  but  sufficiently  to  prove  its  existence.  This 
effect  cannot  be  wholly*  accounted  for  without  supposing  the 
existence  of  a  peculiar  vital  power. 

*  The  heat  which  is  found  in  vegetables  is  partly  due  to  chemical 
changes.     By  the  assimilation  of  the  matter  taken  into  the  tree  by  the 


36  BIOLOGY  OF  PLANTS. 

II.  Eicitahility  in  vegetables  indicates  the  existence  of  a 
vital  principle,  and  is  one  of  its  distinguishing  properties.  It 
is  a  capacity  of  being  acted  upon  by  natural  and  artificial  stim- 
ulants, such  as  light,  heat,  electricity,  manures  and  saline  com- 
pounds. 

1.  Light.  The  stimulating  influence  of  light  upon  the 
leaves  and  blossoms  of  vegetables,  cannot  have  escaped  the 
most  common  observation.  The  leaves  turn  their  upper  sur- 
faces to  the  sun,  and  the  blossoms  of  many  plants  close  during 
the  night,  called  the  deep  of  plants,  and  open  only  when  sub- 
jected to  the  influence  of  that  agent.  Plants  that  grow  in  the 
shade  are  not  so  highly  colored  nor  so  vigorous,  as  those  which 
are  exposed  to  the  light,  and  generally  the  branches  and  the 
fruit  are  the  most  vigorous  on  the  south  side  of  the  tree.  The 
ripe  ears  of  grain  generally  lean  toward  the  south.  The 
branches  grow  in  the  direction  of  a  crevice,  in  the  wall  of  a 
ceflar,  through  which  light  is  admitted.  These,  and  a  great 
variety  of  phenomena  prove  the  existence  of  a  vital  power,  or 
capacity  of  being  excited  by  the  agency  of  light. 

2.  Heat  exerts  a  powerful  influence  upon  the  functions  of 
plants.  This  is  seen  in  the  germination  of  the  seed,  a  certain 
temperature  being  requisite  to  develope  the  germ,  and  enable 
it  to  throw  out  roots  and  stalks.  In  the  production  of  leaves, 
flowers  and  fruit,  each  development  depends,  to  some  extent, 
upon  the  degrees  of  heat  which  are  applied, — hence  the  vari- 
ous means  which  are  employed  to  increase  or  diminish  the 

roots  and  leaves,  gases  and  liquids  arc  converted  into  solids,  and  by  a 
well  known  law  in  such  cases,  heat  is  evolved;  the  insensible  heat  be-, 
comes  sensible ;  on  the  same  principle,  as  the  temperature  of  tlie  air  di- 
minishes, and  the  sap  beg-ins  to  freeze,  a  quantity  of  heat  is  evolved. 
The  power  of  resisting  heat  is  partly  accounted  for  on  the  principle 
that  the  plant  transpires  a  large  quantity  of  water  through  the  leaves, 
and  as  the  heat  increases,  the  quantity  of  water  is  increased ;  by  the 
conversion  of  the  water  into  vapor,  a  large  quantity  of  caloric  becomes 
insensible,  the  external  heat  is  thus  taken  up,  and  the  temperature  of 
the  plant  remains  below  that  of  the  surrounding  medium. 


PROOFS  OF  VITALITY.  37 

temperature  by  hot-houses,  inclosures,  shades,  etc.  The  vi- 
tal energies  of  the  plant  are  nearly  suspended  during  the  win- 
ter season.  But  on  the  return  of  spring,  the  heat  which  it 
brings  with  it,  excites  the  living  functions,  and  enables  the  plant 
to  put  forth  its  leaves ;  and,  as  the  heat  increases,  its  flowers 
and  fruit ;  all  of  which  not  only  prove  the  existence  of  such  a 
principle,  but  also  exhibit  a  most  important  property  of  it. 

3.  Ehitricity  has  probably  a  much  more  powerful  effect 
upon  the  functions  of  vegetables  than  has  been  generally  sup- 
posed, and  tends  powerfully  to  quicken  their  vital  energies. 
Davy  proved  that  seeds  germinate  sooner  in  water,  charged 
with  positive  than  with  negative  electricity. 

4.  Artificial  stimulants,  such  as  manures  and  saline  com- 
pounds, and  even  acids  and  alkalies,  produce  effects  upon  the 
functions  of  vegetables  which  can  only  be  accounted  for  on 
the  ground  that  they  contain  a  vital  power  which  is  peculiar 
to  them,  and  different  from  the  ordinary  agents  of  dead  matter. 

III.  Irritability  is  another  property  of  vegetables  which 
proves  the  existence  of  the  vital  principle.  This  property  is 
conspicuous  in  the  leaves  of  certain  plants,  as  the  sensitive 
plant  and  Venus'  jly  trap  ;  but  is  more  generally  found  in  the 
stems,  stamens  and  tendrils,  as  in  the  pea,  bean  and  vine. 

IV.  The  productions  of  the  vegetable  kingdom  are  decisive 
proofs  of  the  existence  of  a  vital  power.  Most  of  these  pro- 
ductions cannot  be  formed  by  any  known  chemical  agents.* 
The  chemist  can  analyze  them  and  show  their  composition  to 
be  oxygen,  hydrogen,  carbon  and  nitrogen,  with  a  small  quan- 
tity of  alkalies  and  metallic  oxides ;  but  he  has  no  means  of 

*  There  is  hardly  an  exception  to  the  rule,  that  in  producing  orga- 
nic substances,  as  they  are  called,  the  chemist  must  employ  other  or- 
ganic substances  which  are  as  yet  beyond  his  art — which,  so  far  as  we 
know,  can  only  be  formed  under  the  direction  of  the  living  principle. 
In  no  one  case  can  he  form  the  substances  of  which  animals  and  plants 
chiefly  consist,  out  of  those  on  which  animals  and  plants  chiefly  live.^ — 
Johnsons  Lectures, p.  190. 


38  BIOLOGY  OF  PLANTS. 

combining  these  elements  so  as  to  reproduce  them.  The  pro- 
duction of  woody  fibre,  gluten,  starch,  sugar,  gum,  resin, 
vegetable  oils,  acids  and  alkalies,  with  a  few  exceptions,  whol- 
ly exceed  the  power  of  any  known  chemical  or  physical  agent. 
They  can  be  accounted  for  only  by  supposing  a  new  and  pe- 
culiar po\\^er  inherent  in  the  vegetable,  which  we  call  the  pow- 
er of  life  or  the  vital  principle. 

Nature  of  vitality .  Of  this  we  are  wholly  ignorant.  We 
know  it  only  from  its  effects.  Like  affinity  and  attraction, 
it  is  an  ultimate  power,  at  least,  so  far  as  science  is  concerned ; 
for  aught  we  know  it  is  the  direct  power  of  God  exerted  in 
this  particular  way. 

Various  hypotheses,  however,  have  been  suggested  to  ac- 
count for  the  phenomena  of  life.  A  few  of  these  may  proper- 
ly be  introduced  in  this  connection. 

1.  Some,  as  Paracelsus,  held  to  a  spiritual  being.  The 
business  of  digestion  was  performed  by  the  demon  Archaeus, 
who  had  his  abode  in  the  stomach,  and  ''  who,  by  means  of 
his  alchemical  processes,  separates  the  nutritive  from  the 
harmful  parts  of  our  food,  and  makes  it  capable  of  assimila- 
tion. 

2.  Others,  as  Silvius,  conceived  that  the  vital  functions 
were  due  to  chemical  agents,  and  that  the  power  of  life  con- 
sists in  the  action  of  acids  and  alkalies,  in  fermentation  and  the 
like  processes. 

3.  A  third  class  have  proposed  a  mechanical  hypothesis, 
which  originated  about  the  time,  and  was  the  result  of  the 
splendid  discoveries  of  Galileo  and  Newton.  The  phenomena 
of  life  were  due  to  the  form  of  the  particles  of  matter,  their 
motions  and  mutual  attractions. 

4.  A  fourth  class  suppose  the  existence  of  a  vital  jluid,  up- 
on which  the  peculiar  functions  of  life  depend.  This  hypo- 
thesis was  proposed  by  Frederic  Hoffinan  of  Halle,  1()94. 
The  vital  fluid  was  a  material  substance  acting  through  the 
nerves,  and  producing  the  actions  of  all  the  other  organs.  This 


NATURE  OF  VITALITY.  39 

is  the  "  Ether,  which,  diffused  throughout  all  nature,  produces 
in  plants  the  bud,  the  secretion  and  motion  of  the  juices,  and 
is  separated  from  the  blood  and  lodged  in  the  brain  of  an- 
imals." 

5.  A  fifth  hypothesis,  first  proposed  by  Aristotle,  was  re- 
vived by  Stahl,  and  refers  the  phenomena  of  life  to  an  ani- 
mal soul,  or  immaterial  principle  wholly  distinct  from  a  soul,  as 
the  responsible  and  intelligent  part  of  man's  nature.  This 
theory  has  been  adopted  by  many,  but  it  is  evidently  inappli- 
cable to  plants.  This  objection  appears  to  be  fatal  to  its  truth, 
although  the  Physical  School,  as  those  have  been  called  who 
adopted  this  theory,  are  mainly  right  in  this,  that  in  ascribing 
the  functions  of  life  to  a  soul,  "  they  mark  strongly  and  justly 
the  impossibility  of  ascribing  them  to  any  known  attributes 
of  body."* 

Various  attempts  have  also  been  made  to  define  life,  or  to 
analyze  the  idea  of  it. 

1.  The  most  correct  definition  of  life  is  given  by  Bichat, 
and  modified  by  Whewell.  "  Life  is  the  system  of  vital  func- 
tions" These  functions  are  of  two  kinds,  those  which  per- 
tain to  organic  life,  which  are  the  same  both  in  animals  and 
vegetables,  and  those  which  belong  to  animal  life,  which  in- 
clude sensation  and  voluntary  motion. 

2.  Some  suppose  that  the  idea  of  life  is  simple,  and  hence 
the  effects  of  it  are  explained  by  reference  to  a  single  prin- 
ciple. 

3.  Others  attempt  to  separate  life  into  a  series  of  vital  func- 
tions, such  as  secretion,  assimilation,  absorption,  etc.  and 
hence  muke  the  idea  of  it  complex. 

But  in  all  these  attempts,  there  seems  to  be  a  necessity  of 
referring  the  phenomena  of  life  to  some  distinct  force.  This 
force  has  been  variously  denominated  organic  attraction  or 
vital  attraction,  organic  affinity  or  vitcd  affinity.     Professor 

*  See  Whewell's  Philosophy  of  Inductive  Sciences,  Vol.  II,  in 
which  these  and  other  hypotheses  are  examined. 


40  BIOLOGY  OF  PLANTS. 

Mliller  calls  it  organic  assimilation,  and  this  seems  to  accord 
with  the  usage  of  biological  writers. 

But  whatever  name  physiologists  may  give  to  this  power, 
and  whatever  attempts  they  may  make  to  analyze  or  define 
the  idea  of  life,  whether  we  study  it  in  the  separate  functions 
of  secretion,  assimilation,  or  any  other  organic  change,  its 
nature  is  wholly  unknown  to  us.  We  know  what  its  effects 
and  laws  are,  and  can  better  understand  them  by  conceiving, 
as  their  cause,  a  peculiar  poiar,  essentially  distinct  from  the 
ordinary  agents  of  dead  matter,  although  producing  both  me- 
chanical and  chemical  effects. 

But  on  the  supposition  that  such  a  power  exists,  what  influ- 
ence can  it  exert  upon  the  theory  or  practice  of  agriculture  ? 
In  answer  to  this  inquiry,  it  may  be  observed, 

1.  That  it  is  useful  to  have  reference  to  the  irital  power , 
in  the  whole  process  of  tillage.  Regarding  this  power  as  the 
great  agent  in  the  process  of  vegetation,  we  may  refer  all  the 
productions  of  the  farm  to  it  as  a  cause. 

The  science  of  tillage  is  a  knowledge  of  those  laws  by  which 
the  vital  power  is  governed,  and  of  the  conditions  which  are 
necessary  to  its  activity ;  and  practical  farming  consists  in 
acting  according  to  its  laws,  and  in  supplying  those  conditions 
which  are  required  for  its  most  perfect  development. 

I  will  illustrate  the  relation  which  the  vittd  power  in  plants 
sustains  to  the  science  and  practice  of  agriculture,  by  a  refer- 
ence to  the  science  and  practice  of  medicine.  What  is  the 
science  of  medicine?  It  is  a  knowledge  of  those  laws  which 
govern  the  vital  power,  as  it  exists  in  the  hunjan  species,  and 
of  those  conditions  which  are  necessary  to  the  complete  de- 
velopment and  perfection  of  this  power,  including,  of  course, 
whatever  may  obstruct  it  in  its  operations.  And  what  is  the 
practice  of  medicine?  It  is  mainly  concerned  in  applying 
remedies  to  remove  the  obstacles  to  the  proper  action  of  vital- 
ity ;  a  provision  being  made  by  our  Maker  in  our  appetites, 
so  that  we  become  our  own  physicians,  in  supplying  moi?t  of 


USES  OF  VITALITY.  41 

the  conditions,  which  are  necessary  to  keep  up  the  continu- 
ance and  activity  of  this  principle.  But  in  the  vegetable  king- 
dom, nature  has  not  given  to  the  plant  the  power  of  making 
known  its  wants,  but  has  left  it  to  the  farmer  to  learn  what 
they  are,  and,  if  he  wishes  the  seed  or  the  plant  to  develope 
itself  in  the  most  perfect  and  useful  manner,  he  must  supply 
them  with  all  those  conditions,  which  their  peculiar  constitu- 
tion requires.  He  must  become  acquainted  not  only  with  their 
natural  enemies,  but  with  their  particular  friends,  and  defend 
them  from  the  attacks  of  the  former,  by  surrounding  them 
with  the  strong  protection  of  the  latter. 

Unskilful  farming,  like  quackery  in  medicine,  has  but  one 
specific  for  every  species  of  disease.  It  is  a  subject  of  deep 
regret,  that  imicli  of  the  practice  of  medicine,  and  all  kinds 
of  quackery,  are  but  a  series  of  experiments  upon  the  capa- 
bilities of  the  vitcd  pmvcr ;  and,  although  our  Creator,  as  if 
foreseeing  the  trial  to  which  it  would  be  subjected,  has  given 
it  a  wonderful  degree  of  elasticity  and  accommodation  to  cir- 
cumstances, although  he  has  endowed  it  with  an  almost  uncon- 
querable power,  yet  when  it  has  been  long  heatcn,  bruised 
and  abused,  it  will  cry  out  under  its  tortures,  and  make  its  suf- 
ferings known  by  the  emaciated  form,  the  languid  ptdse,  and 
the  feeble  step. 

It  is  scarcely  less  to  be  regretted,  that  quackery  in  farming 
is  little  else  than  experiments  upon  the  capabilities  of  the  vi- 
tal power  in  seeds  and  plants ;  and  although  they  too  have  a 
most  elastic  and  yielding  constitution,  yet  the  neglected  plant 
will  tell  you,  by  its  stinted  growth  and  scanty  fruits,  of  the  vio- 
lence which  is  done  to  its  vital  energies. 

2.  A  correct  view  of  the  vital  power  may  serve  to  awaken 
interest,  and  excite  admiration  in  view  of  the  simple,  yet  beau- 
tiful kws  which  the  Creator  has  established  for  the  production 
and  perpetuation  of  animal  and  vegetable  bodies. 

If  we  take  an  egg,  for  example,  and  examine  it,  we  shall 
find  it  has  a  hard  covering,  composed  of  carbonate  of  lime, 

4 


42  BIOLOGY  OF  PLANTS. 

similar  to  chalk  or  marble ;  and  a  semi-fluid  mass  of  white 
and  yolk  within,  consisting  mostly  of  a  substance  which  chem- 
ists call  albumen.  It  gives  no  signs  of  life.  It  hardly  exhibits 
the  marks  of  organization,  and  yet,  let  that  same  egg  be  sub- 
ject to  warmth  for  a  few  weeks,  and  you  will  find  that  it  has 
been  touched  by  the  life-giving  power  of  the  Creator  ;  that  he 
has  impressed  it  with  a  living  energy,  which  will  soon  be  de- 
veloped in  an  organized,  sensitive  being ;  so  peculiar  in  its 
composition,  that  no  chemist  can  ever  produce  its  like,  so 
perfect  in  every  part  of  its  structure,  that  no  mechanic  can 
form  even  the  smallest  feather  that  tips  the  wing  of  the  chick. 

Or,  if  we  take  a  seed,  a  kernel  of  corn,  and  examine  that, 
we  shall  find  it  a  hard,  dry  substance,  different  in  composi- 
tion and  appearance  from  an  egg,  consisting  mostly  of  mucil- 
age and  starch.  It  too  is  the  most  unlikely  thing  to  be  pos- 
sessed of  vitality.  You  may  keep  it  a  hundred  years,  for  aught 
I  know,  and  it  is  still  the  same  apparently  dead  substance. 
But  only  cast  it  into  the  earth,  subject  it  to  heat  and  moisture, 
and  after  this  long  sleep  of  a  century,*  it  will  also  show,  that 
when  it  was  matured  upon  the  parent  stalk,  perhaps  in  some 
remote  corner  of  the  globe,  the  Creator  treasured  up  and 
guarded  in  it  a  vital  power,  which  will  be  exhibited  by  its  tak- 
ing root  downward,  and  springing  upward  a  living  organized 
body,  provided  with  organs  capable  of  converting  that  which 
contains  the  contagion  of  death  into  the  staff  of  life. 

And  what  serves  to  increase  our  admiration,  is  the  fact, 
that  this  power  is  not  confined  to  a  few  seeds  which  are  es- 

*  Seeds  probably  possess  different  powers  of  life,  some  preserving 
their  vital  principle  through  centuries  of  time,  while  others  have  an 
ephemeral  existence  under  any  circumstances.  The  reasons  for  this 
difference  are  unknown  to  us,  and  apparently  depend  upon  a  First 
Cause,  over  whicli  we  have  therefore  no  control.  *  *  I  have  myself 
raised  raspberry  plants  from  seeds  found  in  an  ancient  coffin  in  a  bor- 
ough in  Dorsetshire,  which  seeds,  from  the  coins  and  other  relics  met 
with  near  them,  may  be  estimated  to  have  been  sixteen  or  seventeen 
hundred  years  old. — Lindlcy. 


DEFINITIONS  AND  DESCRIPTIONS.  43 

pecially  intended  to  perpetuate  the  species,  but  all  alike  are 
endowed  with  it,  whether  intended  for  the  support  of  man  or 
other  animals  ;  whether  cast  on  rocks,  into  the  water,  by  the 
way  side,  or  into  the  fertile  soil.  While  countless  millions  are 
annually  produced,  only  here  and  there  one  is  permitted  to 
engage  in  the  process  of  reproduction  ;  so  provident  has  nature 
been,  so  careful  to  ensure  the  perpetuity  of  the  race. 

3.  A  proper  view  of  the  vital  power  may  serve  to  im- 
press the  tiller  of  the  soil  above  all  other  men,  with  the  most 
important  moral  lessons.  Particular  attention  should  be 
given  to  it  because  it  is  unseen  and  secret  in  its  operations, 
and  is  not  therefore  properly  considered.  No  credit,  so  to 
speak,  is  given  to  it.  And  when  the  farmer  casts  in  his 
seed  and  gathers  his  golden  harvests,  he  forgets  the  most 
important  agent,  which  has  been  working,  with  unceasing  en- 
ergy, to  fill  his  stores  with  food.  Nor  does  he  consider,  while 
enjoying  the  rich  rewards  of  his  industry,  the  benevolent  pro- 
vision of  his  Maker  in  giving  to  every  kernel  of  his  grain  the 
power  of  producing  future  harvests,  and  supplying  future  wants. 

When  he  looks  over  the  face  of  the  earth  and  sees  what  an 
infinite  variety  of  form,  color  and  property,  characterizes  the 
plants  which  everywhere  cover  its  surface,  it  may  serve,  at 
least,  to  humble  his  pride,  and  confound  his  wisdom,  when  he 
reflects  that  he  cannot  tell  how  a  spear  of  grass  grows,  much 
less  impart  a  single  tint  to  the  gorgeous  coloring  with  which 
nature  has  adorned  her  covering.  But  he  may  see  in  every 
stalk  of  grain  the  workings  of  a  hidden  and  mysterious  power, 
the  evidence  of  an  all-pervading  and  beneficent  Intelligence. 

Sect.  2.  Defi,mtions. — Conditions  necessary  to  develope  the  vi- 
tal principle  in  the  seed,  bulb  and  bud. 

1.  A  seed  is  a  living  body,  capable  of  producing  a  new  indi- 
vidual of  the  same  species.  "It  is  a  reproductive  fragment,  or 
vital  point,  containing  within  itself  all  the  elements  of  life."  The 
seed  consists  of  three  parts,  cotyledons,  radicle  and  plumula. 


44 


BIOLOGY  OF  PLANTS, 


2.  Cotyledons  are  the  seed  lobes,  as  in  the  Fio-  5 
garden  bean,  (Fig.  5,)  and  are  composed  of 
matter  to  nourish  the  germ  a  6,  betbre  it 
can  obtain  food  from  the  soil.  Some  seeds 
have  no  cotyledons,  such  as  those  of  the 
mosses  and  ierns,  and  are  called  acotyle- 
donous ;  other  seeds  have  but  one  cotyledon, 
such  as  those  of  grasses,  grains,  etc.  and 
are  called  monocotyledonous ;  otliers  still 
have  two,  as  those  of  leguminous  plants,  (the  pea,)  and  are 
called  bicotyledonous.  A  fourth  class  hav^e  more  than  two  cotyle- 
dons, and  are  called  polycolylcdonoiis^  of  which  the  seeds  of  the 
pine  and  hemlock  are  examples. 

3.  Radicle.  The  radicle  (Fig.  5,  h)  is  that  part  of  the  embryo 
which  shoots  downwards  into  the  earth,  and  forms  the  roots  of 
plants. 

4.  Plumula.  The  plumula,  a^  is  that  part  which  shoots  up- 
ward into  the  air,  and  forms  the  stalk  or  stem,  branches,  leaves 
and  fruit. 

5.  Bulhs  are  tubercles  connected  with  the  roots  of   Fig.  6. 
plants,  and   contain    the  embryo  of  the   future   plant. 
The   potato  (Fig.  6)  is  a   well  known   example  of  a 
bulb. 

6.  Buds  are  vital  points  along  the  stem,  situated 
generally  at  the  axles  or  angles  of  the  leaves.  The 
bud  (Fig.  7, «  c)  is  caj)able  of  forming  leaf  buds,  flowers, 


Fig.  7. 


DEFINITIONS  AND  DESCRIPTIONS.  45 

fruit  or  branches ;  or  when  separated  from  the  stalk,  of  produc- 
ing a  plant,  not  only  of  the  same  species,  but  of  the  same  va- 
riety ;  -while  seeds  produce  similar  species,  but  not  the  same 
varieties. 

7.  Eye  is  a  term  applied  to  vital  points  on  bulbous  roots,  as 
the  potatoe,  (Fig.  6,  a.)  These  {)oints  are  also  found  on  the  stem, 
(Fig.  7,  rf,)and  are  similar  to  the  germ,  or  vital  pouit  of  the  seed. 
Tliey  are  in  fact  the  true  buds. 

8.  Chemical  transformation  is  a  term  applied  to  the  changes 
which  tcike  place  in  compound  bodies,  when  subjected  to  the 
influence  of  other  substances.  If  the  change  consists  simply  in 
the  new  arrangement  of  tlje  atoms  of  the  conijjound,  the  change  is 
called  catalytic  ;  but  when  the  change  takes  place  in  the  organs  of 
plants,  and  consists  in  the  body's  yielding  one  ingredient,  and 
forming  by  its  remaining  elen^ents,  or  by  elements  obtained  from 
the  acting  body,  a  new  compound  ready  to  pass  through  other 
similar  changes,  then  it  is  called  properly  a  transformation  ;  and 
when  a  series  of  changes  are  thus  produced  upon  water,  or  any 
other  substance,  the  body  is  said  to  pass  through  chemical  trans- 
formations. 

"An  organic  chemical  transformation  is  the  separation  of  the 
elements  of  one,  or  of  several  combinations,  and  their  reunion 
into  two  or  several  others,  which  contain  the  same  number  of 
elements,  either  grouped  in  another  manner,  or  in  different  pro- 
portions."— Liehig. 

The  catalytic  force  acts  by  mere  presence.  The  combination 
of  two  bodies  in  contact  with  other  compounds,  causes  the  latter 
to  enter  into  a  similar  state.  The  process  of  fermentation  will 
serve  to  illustrate  the  nature  of  this  force.  A  small  quantity  of 
matter,  in  a  state  of  fermentation,  causes  an  indefinite  quantity 
to  enter  into  a  similar  state,  as  when  yeast  is  introduced  into 
dough. 

9.  A  simple  substance  is  one  which  has  never  been  resolved 
into  two  kinds  of  matter,  such  as  charcoal,  silver,  gold,  iron,  etc. 
The  number  of  simple  substances  is  fifty-five ;  and  they  are  re- 
presented by  letters  or  symbols;  thus,  O  stands  for  Oxygen, 
H.  for  Hydrogen,  C  for  Carbon,  and  N  for  Nitrogen.  The  quan- 
tity in  which  any  body  combines,  is  expressed  in  numbers,  hy- 
di'ogen  being  taken  for  unity.  Only  fourteen  simple  bodies  are 
found  in  vegetables,  of  which  the  following  are  the  names, 
equivalents  and  symbols.  Hydrogen,  symbol  H,  equivalent 
1 ;  Oxygen,  Symb.  O,  Equiv.  8,  and  Nitrogen,  N — 14,  which,  in 

4* 


46  BIOLOGY  OF  PLANTS. 

their  pure  state  are  gaseous  bodies  ;  Carbon  C — 6.12,  Silicon 
Si — 22.5,  Phosphorus  P — 15.7,  and  Sulphur  S — 16.1,  which  are 
called  non-metallic  combustibles,  (and  for  which  Dr.  Dana  has 
proposed  the  term  wrefs) ;  Potassium  K — 39.15,  Sodium  Na — 
23.3,  Magnesium  Mg — 12.17,  Calcium  Ca — 20.5,  Aluminium 
A\ — 13.7,  Iron  Fe — 28,  and  Manganese  Mn — 27.7,  which  are 
metals. 

10.  Compound  Bodies.  A  compound  body  is  one  which  is 
composed,  or  made  up  of  two  or  more  simple  bodies.  The 
number  of  compound  bodies  is  unknown.  They  are  represen- 
ted by  adding  the  symbols  of  the  simple  substances,  which  en- 
ter into  their  composition;  thus,  HO  represents  a  compound 
formed  by  the  union  of  oxygen  and  hydrogen  (water).  The 
equivalent  is  the  sum  of  the  equivalents  of  the  simple  bodies 
thus  combined,  HO=l-|-8=9,  which  is  the  equivalent  for  wa- 
ter. 

11.  When  oxygen  combines  with  any  other  substance,  the 
compound  is  called  an  alkali,  an  alkaline  earth,  an  oxide  or  an 
acid;  thus  potassa,  soda  and  lithia  are  compounds  of  oxy- 
gen with  metals,  and  are  alkalies.  Ahunina,  lime  and  magne- 
sia are  alkaline  earths,  and  oxide  of  iron  and  of  manganese  are 
oxides.  Oxygen  combined  with  nitrogen  forms  nitric  acid ; 
with  sulphur,  silicon  and  carbon,  sulphuric,  silicic  and  carbon- 
ic acids. 

12.  When  acids  unite  with  the  alkalies,  alkaline  earths  or 
metallic  oxides,  the  class  of  bodies  formed  are  called  salts. 
When  the  nuniber  of  the  equivalents  of  an  acid  and  an  al- 
kali are  equal,  the  salt  is  called  neutral.  When  the  alkali  is  in 
excess,  the  salts  are  called  by  some  sub-salts,  and  when  the 
acid  is  in  excess  they  are  sometimes  called  super-salts.  The 
name  of  the  salt  terminates  in  ate,  as  phosphates,  carbonates, 
nitrates.  When  carbon,  phosphorus,  silicon  and  sulphur  unite 
with  each  other  or  with  the  metals,  they  are  termed  carburets, 
phosphurets,  siliciurets  and  sulphurets. 

13.  An  acid  and  an  alkali  unite  in  definite  proportions,  and 
mutually  neutralize  each  other.  TJuis,  40  parts  of  sulpliuric 
acid  is  neutralized  by  48  of  potash,  or  20  of  magnesia,  or  28  of 
lime,  or  32  of  soda,  or  17  of  ammonia  ;  hence  these  alkalies  may 
be  substituted  for  each  other,  whatever  acid  is  used  ;  and  the 
same  is  true  of  acids — hence  the  term  equivalent,  because  they 
may  be  substituted  for  each  other,  and  form  neutral  salts. 

14.  Almost  the  entire  mass  of  every  vegetable  may  be  resol- 
ved into  two  or  more  of  four  simple  bodies,  viz.,  oxygen,  hydro- 


DEFINITIONS  AND  DESCRIPTIONS.  47 

gen,  carbon  and  nitrogen.  These  are  called  the  organic  constitu- 
ents of  plants,  because  when  any  jjortion  of  vegetable  matter  is 
burned,  it  either  disappears  entirely,  or  leaves  behind  a  small 
quantity  of  ash. 

15.  The  ash  is  composed  of  several  simple  bodies,  and  hence 
these  latter  are  caHed  the  inorganic  constituents  of  plants. 

Sonje  knowledge  of  the  organic  constituents  of  plants,  ap- 
pears to  be  necessary  for  understanding  the  subject  of  this  sec- 
tion, and,  for  the  information  of  those  who  have  not  attended  to 
elementary  chemistry,  a  short  description  of  them  is  here  in- 
serted. 

1.  Oxygen  is  found  in  the  state  of  a  gas  in  the  atmosphere, 
mixed  with  nitrogen,  and  constitutes  one  fifth  part  of  its  vol- 
ume;  eight-ninths  of  water  by  weight  is  also  oxygen  gas.  Be- 
side this,  the  whole  crust  of  the  globe  is  composed  of  oxydized 
substances,  that  is,  of  substances  combined  with  oxygen. 

In  its  pure  state,  oxygen  is  a  transparent  gas,  without  color, 
odor  or  taste,  and  is  a  little  heavier  than  the  air.  It  unites 
chenjically  with  a  great  number  of  substances.  If  a  lighted  ta- 
per is  plunged  into  it,  the  brilliancy  of  thd  flame  is  much  in- 
creased, and  if  heated  iron  be  immersed  in  a  jar  of  pure  gas, 
the  combustion  is  so  intense  as  to  melt  and  burn  the  iron.  This 
substance  is  always  one  of  the  agents  in  all  our  fires  and  lights  ; 
hence  its  importance.  Oxygen  also  is  the  supporter  of  the  res- 
piration of  animals.  No  animal  can  live  for  any  length  of  time 
without  it.*  It  is  no  less  essential  to  the  existence  of  the  veg- 
etable kingdom. 

2.  Hydrogen  is  chiefly  found  in  water,  forming  one-ninth  part, 
from  which  it  may  be  obtained  by  putting  into  it  iron  or  zinc 
turnings  and  sulphuric  acid.  It  is  found  in  most  liquids,  and 
in  all  animai  and  vegetable  bodies. 

Hydrogen  in  its  pure  state  exists  in  the  form  of  a  gas,  no  way 
distinguished  in  its  physical  properties  from  oxygen,  with  the 
exception  of  its  being  sixteen  times  lighter,  and  a  much  more 
pow^erful  refractor  of  light.  When  a  lighted  taper  is  inmiersed 
in  it,  the  hydrogen  is  set  on  fire,  but  the  taper  is  extinguished. 
If  air  or  oxygen  gas  is  mixed  with  it,  and  the  flame  of  a  candle 
brought  in  contact,  the  mixture  will  explode,  and  the  product 
will  be  water.  Animals  are  suffocated  by  it,  and  balloons  ai-e 
made  to  ascend. 

Water.  One  part  of  hydrogen  and  eight  of  oxygen,  by  weight, 

^  See  Gray's  Chemistry,  p.  131. 


48 


BIOLOGY  OF  PLANTS. 


form  water,  (Symb.  HO.  eq.==9),  a  substance  remarkable  in  its 
relation  to  vegetation  from  the  ease  with  which  it  is  decompo- 
sed, when  subjected  to  the  influence  of  the  vital  principle,  as  it 
passes  with  great  facility,  through  several  transformations  in  the 
vegetable  organs. 

3.  Carbon  is  the  most  abundant  substance  in  vegetable  bo- 
dies. In  its  pure  state,  it  exists  as  the  most  valued  and  beauti- 
ful of  gems — the  diamond.  Common  charcoal  is  nearly  pure 
carbon.  All  kinds  of  coal  are  essentially  composed  of  it ;  great 
quantities  are  also  locked  up  in  the  rocks,  in  the  form  of  car- 
bonic acid,  (fixed  air).  Common  charcoal  is  a  well  known  sub- 
stance ;  it  burns  with  a  white  ligiit,  but  with  little  flame.  As  it 
constitutes  from  40  to  50  per  cent,  of  all  vegetables,  it  has  much 
to  do  in  the  processes  of  vegetation.  One  of  its  most  impor- 
tant properties  is  the  power  of  absorbing  several  gases,  a  pro- 
perty upon  which  its  utility  as  a  maniu-e  depends. 

Carbonic  acid.  Carbon  coml)ines  with  oxygen,  and  forms  car- 
bonic acid,  or  fixed  air.  This  is  a  gaseous,  transparent  sub- 
stance, two  and  a  half  times  heavier  than  common  air.  It  is 
composed  of  one  equivalent  of  carbon,  6.12,  and  two  of  oxTgen, 
16  =  22.12.  Its  symbol  is  CO^.  Carbonic  acid  is  readily  ab- 
sorbed by  water,  to  which  it  imparts  a  sour,  lively  taste  ;  also  a 
brisk,  sparkling  flavor  to  all  fermented  drinks,  as  beer.  It  is 
sup{)osed  to  yield  more  carbon  to  plants  than  all  other  substan- 
ces united. 

4.  JViti'ogen  exists  in  the  atmosphere,  of  which  it  forms  80  per 
cent.  It  is  never  absent  from  any  part  of  the  vegetable  struc- 
ture, but  exists  in  small  quantities.  Animals  contain  larger 
quantities  of  it. 

Nitrogen  is  a  transparent  gas,  without  color,  odor  or  taste. 
It  is  distinguished  for  its  negative  properties,  for  it  will  neither 
support  life  nor  combustion,  but  appears  to  act  simply  as  a  di- 
luent to  the  oxygen  of  the  atnjos{)here.  Its  compounds,  how- 
ever, are  among  the  most  active  and  useful  substances. 

Nitric  add,  (NO^)  commonly  called  aquafortis,  is  a  com- 
pound of  nitrogen  and  oxygen.  It  exists  both  in  the  gaseous 
and  liquid  state  and  is  highly  corrosive  and  active  in  its  proper- 
ties. In  combination  with  potassa,  forming  nitre,  and  with  other 
alkalies,  it  is  supposed  to  perform  important  offices  in  vegeta- 
tion. 

Ammonia  is  well  known  as  hartshorn.  It  is  composed  of  ni- 
trogen and  hydrogen,  (NIP)  and  exists  as  a  gas,  but  is  rapidly 


GERMINATION.  49 

absorbed  by  water.  In  its  pure  state  it  is  a  powerful  alkali,  of 
a  caustic  and  burning  taste,  and  pungent  odor.* 

It  resembles  water  in  the  circumstance  of  being  easily  de- 
composed in  the  vegetable  organs.  The  alkahes  are  tested  by 
their  turning  vegetable  blue  c(>lors  green.  Acids  are  tested  by 
their  inij)arting  to  the  same  vegetal)le  infusions  a  red  color. 

With  these  definitions  and  descriptions  the  reader  is  prepar- 
ed to  attend  to  the  sidjject  of  this  section. 

Germination.  The  development  of  vitality  in  the  seed,  or 
germ,  is  called  the  process  o{ germination^  by  which  process 
the  embryo  is  extracted  from  its  envelopes,  and  converted 
into  a  plant.  The  conditions  necessary  to  excite  the  vitality 
of  the  seed  are  three  :  access  to  moisture,  to  air  or  oxygen 
gas,  and  to  heat. 

1.  Moisture.  Seeds  which  are  fully  matured  and  dry  will 
retain  the  vital  power  in  an  inactive  state  for  a  long  time,  if 
no  water  is  present,  because  this  agent  is  necessary  to  facili- 
tate the  chemical  changes  which  must  take  place,  before  it 
can  be  called  into  action.  The  first  effect  produced  by  wa- 
ter, is  to  penetrate  the  outer  covering  of  the  seed.  The  effect 
is  purely  physical,  and  takes  place  equally  well  in  the  dead 
and  living  seed.  A  grain  of  wheat,  or  corn,  for  example,  de- 
prived of  its  vital  principle,  will  absorb  water,  and  become 
putrescent,  while  one  which  still  possesses  vitality  will,  by 
imbibing  moisture,  develope  a  succession  of  new  and  living 
powers.  The  second  effect  of  water,  is  to  yield  oxygen  to  the 
carbon  of  the  germ,  and  form  carbonic  acid,  which  soon  en- 
velopes the  seed.  The  decomposition  of  the  water  is  effected 
by  the  vital  power  of  the  seed.  The  hydrogen  of  the  water 
is  supposed  to  combine  with  the  oxygen  of  the  air,' and  form 
water  again.  Few  seeds,  however,  will  complete  the  process 
of  germination,  when  wholly  immersed  in  water,  especially  if 
air  is  excluded ;  hence  the  injurious  influence  of  a  very  wet 
soil,  or  a  wet  season,  at  the  time  of  planting  the  seed. 

*  For  a  fuller  description  of  the  simple  and  compound  bodies,  see 
Gray's  Chemistry, 


50  BIOLOGY  OP  PLANTS. 

2.  Ai?\  The  oxygen  of  the  air  is  an  active  agent  in  the 
process  of  germination.  Seeds  will  not  germinate  when 
placed  in  a  vacuum;  in  an  atmosphere  of  carbonic  acid,  of 
nitrogen,  hydrogen,  or  of  any  other  gas,  which  does  not  con- 
tain oxygen.  The  principal  .substance  exhaled  during  the 
process  is  carbonic  acid.  According  to  Liebig  a  small  quan- 
tity of  acetic  acid  and  ammonia  are  also  formed  during  the 
process.  These  gases  form  an  atmosphere  around  the  seed, 
unless  it  comes  in  contact  with  water.  The  volume  of  oxy- 
gen consumed  is  equal  to  that  of  the  carbonic  acid  produced. 
The  oxygen  of  the  air  either  combines  directly  with  the  car- 
bon,* or  with  the  hydrogen  of  the  decomposed  water  ;t  hence 
this  appears  to  be  either  a  true  process  of  decay,  or  of  com- 
bustion, and  were  it  not  for  the  vital  force,  the  seed  would 
soon  be  separated  into  its  original  elements.  As  the  oxygen 
of  the  air  is  absolutely  essential  to  germination,  some  have 
supposed  that  the  reason  why  seeds  buried  too  deep,  or  in  a 
stiff  soil,  will  not  germinate,  is  that  they  are  not  reached  by  it, 
and  have  inferred  the  importance  of  ascertaining  the  proper 
depth  for  the  different  kind  of  seeds  in  order  to  facilitate  the 
process.  On  the  same  principle  they  account  for  the  fact, 
that  after  deep  tillage,  plants  often  make  their  appearance, 
which  have  been  cultivated  upon  the  soil  several  years  before. 
But  it  should  be  remembered  that  seeds  thus  situated  are  also 
deprived  of  other  necessary  conditions  of  which  the  absence 
of  the  oxygen  of  the  atmosphere  is  probably  the  least  impor- 
tant. Carbonic  acid  which  is  highly  useful  to  the  plant  is 
supposed  to  be  injurious  to  germination  by  excluding  the  oxy- 

*  "  The  very  first  act  of  life  in  a  seed  is  to  evolve  carbonic  acid  by 
its  carbon  combining  with  oxygen  of  air,  and  its  second  act  is  to  de- 
compose water." — Dana. 

t  "  Water  is  decomposed  l)y  their  vital  force  ;  and  its  oxygen,  com- 
bining with  the  carbon,  forms  carbonic  acid."  "  Seeds  have  the  pow- 
er of  decomposing  water  wliich  causes  the  commencement  of  germi- 
nation. ' ' — Lindiey. 


GERMINATION.  51 

gen  of  the  air.  Hence,  as  the  acid  is  often  produced  in  the 
soil,  in  larger  quantities  than  in  the  air,  some  have  ascribed 
the  favorable  influence  of  lime  and  alkalies  upon  germination 
to  the  fact,  that  they  absorb  carbonic  acid. 

For  a  similar  reason  seeds  should  not  be  sown,  or  planted 
in  direct  contact  with  green  or  fermenting  manures,  as  the 
process  of  fermentation  evolves  large  quantities  of  carbonic 
acid,  in  addition  to  that  which  the  seed  gives  out  in  the  pro- 
cess of  germination.  This  view  has  been  given  to  explain 
a  fact  which  farmers  have  learned  by  experience,  that  when 
green  manures  are  placed  in  the  hill,  the  corn  planted  upon 
it,  will  not  come  up  so  well,  as  when  the  manure  is  spread, 
and  incorporated  with  the  soil.  But  it  is  impossible  to  see 
why  the  carbonic  acid  produced  in  this  process  should  not 
prove  beneficial  rather  than  injurious,  for  this  acid  is  imme- 
diately employed  to  decompose  the  rocks,  and  eliminate  the 
potash,  or  other  alkalies,  which  are  required  to  render  the 
food  soluble,  and  fitted  to  be  absorbed  by  the  plant,  the  in- 
stant its  organs  are  sufficiently  developed  to  receive  it  from 
the  soil.  The  more  probable  reason  for  the  injurious  effects 
of  green  manures  upon  the  soil  is,  that  they  impart  too  much 
nourishment,  and  injure  the  plant,  by  yielding  more  food  than 
its  organs,  in  this  incipient  state,  can  digest. 

3.  Heat.  The  third  condition  necessary  to  germination, 
is  a  proper  temperature.  No  seed  has  been  known  to  ger- 
minate at,  or  below  the  freezing  point  of  water  ;  hence,  seeds 
do  not  germinate  during  the  winter,  although  all  other  con- 
ditions are  supplied.  The  vital  principle,  however,  is  not  al- 
ways destroyed,  but  is  developed  on  the  return  of  spring, 
when  the  temperature  has  arrived  at  the  proper  degree.  The 
requisite  degree  of  temperature  varies  from  60°  to  80°  F. 
The  precise  temperature  depends  upon  the  nature  of  the 
seed,  or  plant.  This  accounts  for  the  fact,  that  different 
seeds  germinate  at  different  seasons  of  the  year  ;  hence  the 
importance  to  the  farmer  of  ascertaining  the  degree  of  tern- 


62  BIOLOGY  OF  PLANTS. 

perature  requisite  to  the  germination  of  the  various  seeds, 
which  are  cultivated  upon  the  farm  ;  hence,  too,  we  see  the 
reason  and  necessity  of  green  and  hot  houses,  to  produce  the 
requisite  temperature  for  the  germination  of  those  seeds,  which 
are  to  furnish  the  earlier  vegetables.  Heat  further  promotes 
germination,  by  producing  those  transform-ations  which  must 
take  place  in  the  starch  and  gum  of  the  seed,  and  which 
both  the  external  heat,,  and  that  generated  within  the  seed 
duing  the  process,  is  employed  in  producing. 

4.  Light  was  formerly  supposed  to  retard  the  process  of  ger- 
mination, but  according  to  the  experiments  of  M.  de  Saus- 
sure,  it  takes  place  in  the  same  space  of  time,  in  the  light  as 
in  darkness,  provided  the  light  does  not,  by  the  heat  contained 
in  it,  dry  up  the  skins  of  the  seed  ;  but  as  this  generally  takes 
place,  the  burying  of  the  seed  in  the  soil  a  few  inches  is 
most  favorable  to  the  process,  as  the  light  is  excluded,  while 
heat,  moisture  and  air  are  freely  admitted. 

The  process  of  germination  then,  and  the  changes  which 
take  place,  may  be  reduced  to  the  following  particulars. 

L  Water  penetrates  the  coats  of  the  seed,  causing  it  to 
swell,  which  facilitates  the  introduction  of  the  oxygen  con- 
tained in  the  water,  and  in  the  atmosphere  to  all  its  parts. 

2.  The  oxygen  of  the  water  thus  introduced  combines  chem- 
ically with  the  carbon  which  is  the  principal  substance  of  the 
seed,  forming  carbonic  acid  ;  and  the  oxygen  of  the  air  with 
the  hydrogen  of  the  water,  forming  water.  The  carbonic  acid 
acts  upon  the  alkalies,*  and  these  react  upon  the  vegetable 
matter  and  convert  it  into  vegetable  food. 

3.  The  caloric  necessary  to  the  process  increases  the  chem- 

*  When  woody  fibre  or  vegetable  matter  is  brought  into  contact  with 
any  alkali,  it  enters  into  a  process  of  rapid  decay,  and  is  soon  convert- 
ed into  a  substance  capable  of  being  held  in  solution  by  the  water,  and 
of  entering  the  organs  of  plants.  Jlence  the  use  of  potash,  lime,  etc. 
in  the  process  of  germination,  and  during  the  growth  of  plants.  Alka- 
lies are  powerful  converters  of  vegetable  matter  into  food. 


GERMINATION. 


53 


Fig.  8. 


ical  action  between  the  oxygen  and  the  carbon,  and  tends  to 
volatilize  the  carbonic  acid  which  escapes  in  the  form  of  gas, 
at  the  same  time  it  excites  the  germ,  and  stimulates  its  devel- 
opment. 

4.  By  abstracting  a  portion  of  the  carbon  from  the  mucilage 
and  starch,  of  which  the  seed  is  mostly  composed,  a  sweetish 
milky  substance  containing  sugar  is  formed,  which  is  the  first 
nourishment  of  the  embryo  plant. 

Here  we  may  notice  a  very  beautiful 
provision  ;  the  embryo  rejects  all  nour- 
ishment from  the  soil,  but  nature  has 
stored  up  in  the  seed  itself,  a  most  nu- 
tricious  substance,  fully  adequate  to 
all  its  wants.  Fig.  8,  h  cJ,  represents 
the  seed  lobes  containing  the  nourish- 
ment of  the  embryo  c  a,  with  the  fine 
tubes  which  convey  it  to  the  germ. 

The  radicle  c,  Fig.  9,  gives  the  first  indication 
of  vitality,  expanding  and  bursting  its  envelopes^ 
and  at  length  fixing  itself  in  the  soil.  The  plum- 
ula  a,  next  unfolds  itself,  developing  the  rudiments 
of  leaf,  branch  and  trunk  ;  finally  the  seminal 
leaves  gradually  drop  oflf,  and  the  seed  is  converted 
into  a  plant,  capable  of  deriving  nourishment  di- 
rectly from  the  soil,  and  from  the  atmosphere. 

5.  During  this  process,  the  gluten  of  the  seed  is  partially 
changed,  and  forms  a  substance  called  diastase.  This  sub- 
stance appears  to  act  an  important  part.  It  has  the  power  of 
transforming  starch,  first  into  gum,  and  then  into  grape  sugar. 
One  part  of  diastase  will  convert  2000  parts  of  starch  into 
this  substance.  The  necessity  for  this  change,  is  due  to  the 
insolubility  of  the  starch ;  on  which  account,  it  cannot  enter 
into  the  circulation.  The  diastase  is,  therefore,  formed  at 
the  point  where  the  germ  issues  from  the  mass  of  food,  and 
converts  the  starch  into  a  soluble  form,  that  it  may  be  easily 

5 


54  BIOLOGY  OF  PLANTS. 

conveyed  into  the  organs  of  nutrition.  As  soon  as  this  stored 
nutriment  is  exhausted,  the  diastase  itself  is  transformed,  and 
enters  into  the  plant. 

6.  ^rr^/r  «f?'c?  is  also  formed  in  the  process.  This  is  proved 
by  the  fact,  that  when  seeds  are  made  to  germinate  in  pow- 
dered chalk,  after  a  little  while,  acetate  of  lime  may  be  wash- 
ed out  from  it.  This  substance  is  very  soluble  in  water,  and 
the  agency  of  the  acid  according  to  Liebig  is  to  combine 
with  lime  and  earthy  substances,  and  convey  them  into  the 
roots  of  plants.  But  since  the  experiments  of  Braconnot  ren- 
der it  probable  that  acetate  of  lime  is  injurious  to  plaAts,  this 
special  function  of  the  acid  may  well  be  doubted.  It  may  aid 
in  converting  cane  sugar  or  starch  into  grape  sugar,  as  it  is 
fully  established  that  such  changes  take  place,  when  these 
substances  are  brought  into  contact  with  a  dilute  acid.  When 
the  sprout  starts  up,  the  sugar,  under  the  influence  of  light,  is 
converted  into  looody  fhre.  This  does  not  take  place  until 
the  true  or  second  leaf  is  expanded. 

The  period  required  for  the  germination  of  various  seeds, 
when  the  requisite  conditions  are  supplied,  depends  upon  the 
nature  of  the  plant,  that  is,  upon  the  peculiar  constitution  or  ac- 
tivity of  the  vital  principle.  The  vitality  of  some  seeds,  like  that 
of  the  smaller  grains,  peas,  etc.  are  quickly  excited ;  those  of 
corn,  and  most  of  the  vines  require  a  longer  period ;  while  the 
stone  fruits,  and  many  of  the  nuts,  require  wrecks,  and  even 
months,  before  they  will  indicate  any  signs  of  life. 

The  germination  of  seeds  may  be  promoted  by  adding  sub- 
stances to  them,  either  before,  or  after  they  are  sown. 

1.  Immersing  seeds  in  hot  water  has  been  found  to  pro- 
mote germination.  This  is  particularly  desirable  in  the  case 
of  parsnips,  carrots  and  beets,  whose  vital  powers  are  not 
easily  excited  by  the  ordinary  temperature  and  moisture. 

2.  Mr.  Bowie  states,  that  "  he  found  the  seeds  of  nearly  all 
leguminous  plants  germinate  more  readily,  by  having  water 
heated  to  21)0°,  or  even  to  the  boiling  point  of  Fahrenheit's 


GERMINATION.  55 

scale,  poured  over  them,  leaving  them  to  steep,  and  the  water 
to  cool  for  twenty-four  hours,"  and  some  seeds  have  germina- 
ted readily,  when  boiled  for  five  minutes.  There  is  danger, 
however,  if  the  water  is  too  hot,  that  the  vitality  of  most  seeds 
will  be  destroyed. 

3.  By  mixing  seeds  with  substances  wliich  yield  oxygen 
readily,  germination  is  promoted.  Under  ordinary  circum- 
stances, oxygen  is  furnished  from  the  decomposition  of  water, 
by  the  vital  force ;  but  when  this  force  is  languid,  the  supply 
of  this  agent  from  other  sources  is  of  the  highest  utility. 
Humboldt  employed  a  dilute  solution  of  chlorine. which  tends 
to  decompose  the  water,  through  its  affinity  for  hydrogen,  with 
which  it  combines,  and  sets  the  oxygen  at  liberty. 

Mr.  Otto  of  Berlin  employed  oxalic  acid,  which  exerted 
such  an  influence  upon  the  vitality,  that  old  seeds  which  would 
otherwise  die,  are  made  to  germ.inate  readily.  In  all  these 
cases,  however,  there  is  often  danger  of  injuring  the  vitality 
of  the  seed,  by  yielding  too  much  oxygen,  and,  with  a  few  ex- 
ceptions, the  ordinary  conditions  are  the  best  for  the  purposes 
of  agriculture.  The  gardener  may  derive  essential  aid  by  em- 
ploying these  artificial  methods  of  facilitating  the  germination 
of  his  seeds. 

Seeds  seem  to  be  the  appropriate  parts  of  the  plant  from 
which  a  new  individual  is  derived,  and  it  appears  to  be  the 
great  end  of  all  the  vegetable  functions  to  mature  and  fit 
them  for  this  office.  But  although  the  seed  is  the  principal 
means  of  propagation,  it  is  not  the  only  mode  ;  propagation 
may  be  effected  by  means  of  hulhs,  buds  and  leaves.  The  ex- 
citement of  the  vitality  of  bulbs  and  buds,  depends  upon  the 
same  conditions,  as  that  of  the  seed,  although  the  chemical 
changes  are  not  so  complicated.  The  power  of  propagating 
plants,  by  any  other  means  than  by  seeds,  depends  wholly  up- 
on leaf  buds,  (Fig.  7,)  or  upon  what  is  technically  called 
"  eyes ;"  these  are  found  on  the  bulbs,  and  on  the  stem  of  the 
plant,  where  they  are  called  buds.     They  are  in  fact  rudimen- 


56  BIOLOGY  OF  PLANTS. 

tary  branches,  containing  the  elements  of  independent  exist- 
ence. Some  of  them  fall  off,  as  in  several  kinds  of  lily,  and 
take  root,  and  form  a  new  plant,  while  others  remain  attach- 
ed to  the  stem  or  root. 

Although  all  plants  seem  capable  of  being  propagated  by 
eyes,  only  a  few  are  actually  produced  in  this  way.  The  po- 
tato and  the  vine  are  almost  the  only  examples  of  the  use  of 
eyes  for  this  purpose,  unless  propagation  by  slips,  by  budding 
and  grafting,  may  come  under  this  designation. 

The  development  of  vitality  in  the  potato  root  is  similar  to 
that  of  the  seed.  The  eye  corresponds  to  the  germ,  and  the 
bulb  to  the  lobes  of  the  seed.  The  matter  necessary  to  sup- 
ply the  shoot  with  food,  is  treasured  up  in  the  bulb,  just  as  that 
is  in  the  seed  lobes  which  nourishes  the  germ  of  the  seed. 

An  eye  from  a  branch  of  the  vine  being  cut  off  with  a  small 
portion  of  the  wood,  and  placed  under  the  same  conditions 
with  the  seed  or  bulb,  will  soon  throw  out  roots  and  branches. 
The  wood  furnishes  the  nourishment  required,  before  it  can 
derive  it  from  the  soil ;  for  if  the  eye  has  no  wood  attached  to 
it,  life  will  not  be  supported,  and  it  will  die.  Other  plants 
may  be  propagated  in  this  way,  but  the  buds  and  bulbs  of  most 
plants  possess  too  little  vitality  to  be  successfully  employed  for 
this  purpose.  Many  plants,  however,  may  be  easily  propaga- 
ted by  small  branches,  called 

Cuttings.  When  these  are  subjected  to  the  proper  condi- 
tions of  temperature  and  moisture,  their  buds  give  rise  to  new 
individuals,  capable  of  maintaining  a  separate  existence. 

Propagation  hy  layers  is  the  same  as  the  above,  witli  this 
difference.  A  layer  is  a  branch  bent  into  the  earth  and  half 
cut  through  at  the  bend.  When  this  has  thrown  out  roots  in- 
to the  soil,  it  may  be  separated  from  the  tree.  The  Ficus 
Indicus,  in  its  natural  state,  propagates  itself  in  this  way. 

Suckers  are  also  employed  for  the  propagation  of  plants. 
They  are  sprouts  sent  up  from  the  roots  of  trees  and  shrubs, 
and  make  their  appearance  most  frequently  when  the  tree  is 


DEFINITIONS  AND  DESCRIPTIONS. 


57 


cut  down,  because  the  nourishment  in  the  roots  has  nothing 
to  absorb  it,  and  hence  it  forces  up  branches  for  this  purpose. 

In  all  these  cases,  as  well  as  in  those  of  budding  and  graft- 
ing, the  principle  is  the  same  ;  "  the  vital  points,"  are  placed 
under  fitting  conditions  of  air,  moisture  and  temperature,  and 
they  become  converted  into  new  individuals.  Even  the  leaf 
is  capable  of  forming  buds  and  of  continuing  the  species  ;  each 
according  to  the  great  law  of  organized  beings,  propagates  its 
own  species  ;  and  in  all  cases  but  one  the  same  variety  of  the 
species.     The  seed  only  preserves  the  same  species. 

The  propagation  of  plants,  by  their  pjg  xq 

several  organs,  shows  the  bountiful  pro- 
vision of  nature  to  secure  the  continu- 
ance of  the  species.  The  vital  points 
are  the  same,  whether  found  in  the 
seed,  bulb,  bud  or  leaf  The  different 
organs,  as  has  been  shown  by  Goethe, 
are  only  developments  of  one  simple 
germ.  The  leaf  buds,  (Fig.  10,) 
scales,  blossoms,  stamens,  pistils,  fruit 
and  branches  are  only  a  development 
from  one  simple  structure.  The  germ 
is  converted  into  roots  or  stems,  or  any  other  organ ;  hence 
we  should  expect  to  find  the  vital  points  or  eyes  in  all  the  or- 
gans, as  they  are,  in  fact,  the  same  organ  under  different 
forms,  and  are  easily  transformed  into  each  other.  We  see 
these  transformations  going  on  around  us.  In  the  cultivated 
roses,  the  stamens  become  petals.  In  the  pofentilla  nepalensis 
the  flowers  change  into  branches,  and  the  sepals,  petals  and 
stamens  are  converted  into  leaves. 


Sect.  3.    Definitions. — Conditions  of  the  Growth  of  Plants. 

1.  Soil.  Soil  is  decomposed  or  crumbled  rock,  mingled  with 
a  certain  portion  of  animal  and  vegetable  matter,  called  humus, 
or  vegetable  mould. 

5* 


58  BIOLOGY  OF  PLANTS. 

2.  Siih-soil.  The  sub-soil  lies  immediately  below  the  soil,  and 
is  mostly  destitute  of  vegetable  matter. 

The  parts  of  plants  which  are  concerned  in  nutrition  are  the 
root,  stem  and  leaves. 

1.  Root.  The  root  is  that  part  of  the  plant  Fig.  11. 

which  penetrates  the  soil.  The  following  are 
some  of  the  different  varieties  of  roots  :  tap 
roots,  as  in  lucern  and  clover ;  spindle  roots, 
as  in  tlie  carrot,  parsnip  and  beet ;  branching 
roots,  as  in  most  forest  trees ;  fibrous  roots, 
as  in  the  grasses  and  most  annual  plants ;  creep- 
ing roots,  as  in  the  strawberry  ;  tuberous  roots, 
as  the  potato,  and  bulbous  roots,  as  in  the 
fleshy  plants,  the  onion,  turnip,  (Fig.  11, a,)  which  are  composed  of 
regular  concentric  layers  of  vegetable  matter.  Roots  increase 
in  length  by  the  addition  of  matter  to  their  points.  When  this 
matter  is  first  added  it  is  soft,  and  possesses  the  properties  of  a 
sponge,  to  absorb  the  gaseous,  or  liquid  bodies,  which  are  pre- 
sented to  it.  On  this  account  the  points  b,  are  called  sponge- 
lets  or  spongioles.  It  is  through  these,  that  most  of  the  nour- 
ishment derived  from  the  soil,  is  conveyed  into  the  organs  of 
the  plant.  The  roots  are  also  supposed  to  excrete  matter  into 
the  soil,  which  having  passed  through  all  the  transformations 
it  is  capable  of  in  its  descent  from  the  leaves,  is  now  rejected 
as  unfitted  to  nourish  the  plant.  The  root  is  also  supposed  to 
have  the  power  of  selecting  those  substances  which  the  wants 
of  the  Yjlant  require,  as  the  same  species  will  absorb  unequal 
quantities  of  different  substances  wlien  presented  to  them. 
But  the  discriminating  and  excretory  power  has  been  doubted, 
and  these  functions  of  the  root  are  not  yet  fully  established. 

2.  Stem  or  Culm.  The  stem  (Fig.  12)  is  made  up  of  bundles  of 
small  tubes,  extending  from  the  roots  to  the  leaves,  in  which  sap 
and  air  circulate.  The  bark  coutains  similar  tubes  for  the  de- 
scent from  the  leaves  of  the  cambium,  or  elaborated  juices. 
The  stem  contains  the  pith  c,  which  consists  of  tubes  disposed 
horizontally,  and  forming  by  the  medullary  rays,  a  communica- 
tion with  the  bark  ;  but  so  far  as  experiments  have  been  tried 
with  colored  solutions,  the  pith  does  not  serve  the  purpose  of 
circulating  the  sap.  The  tubes  of  the  wood  aid  the  ascent  of 
the  sap,  which,  in  its  progress  upward,  is  sid)jected  lo  certain 
chemical  changes,  and  it  is  supposed  by  some  that  the  various 
gaseous  bodies,  which  <ire  in  the  wood,  and  ascend  to  the  leaves, 
are  produced  by  transformations  in  the  c>ap  in  its  progress  up- 


DEFINITIONS  AND  DESCRIPTIONS. 


59 


ward.     The  vessels  of  the  wood,  Fig.  12. 

like  the  roots  appear    to  possess 

the  power  of  discrimination,  as  to 

what  substances  they  will  receive. 

When,  for  example,  the  trunks  of 

several  trees,  of  the  same  species, 

are   cut  off  above  the  roots,  and 

immersed  in  solutions  of  different 

substances,  some  of  these  solutions 

will  quickly  ascend  in  the  tubes, 

and    penetrate    the    entire    mass, 

while  others  will  not  be  admitted 

at  all,  or  very  slowly,  by  the  vessels 

of  the  tree.     The  functions  of  the 

stem  are  performed  mostly  by  the 

alburnum,  or  sap-wood. 

The  branches  or  twigs  are  ex- 
tensions of  the  trunk,  as  a  h, 
Fig.  12. 

S.  Leaves  are  still  further  extensions  of  the  wood,  and  of  the 
bark.  The  fibres  of  the  leaves  are  minute  tubes  of  Avoody  mat- 
ter, connected  with  the  w^ood,  from  which  they  receive  the  sap. 
The  green  part  of  the  leaf  is  an  expansion  of  the  bark.  The 
sap  descends  from  this  part  into  the  bark,  and  thence  to  the 
root.  Hence,  the  leaf  consists  of  two  layers  of  veins  or  fibres, 
covered  by  a  thin  membrane,  (the  epidermis,)  which  is  an  ex- 
pansion of  the  outer  bark.  This  membrane  is  filled  with  small 
apertures,  for  the  absorj)tion  and  transpiration  of  gaseous 
and  liquid  bodies.  These  pores  (stomata)  on  the  upper  surface 
are  supposed  to  exhale,  and  those  on  the  under  side  of  the  leaf 
to  inhale  substances.  They  will  not  absorb  all  bodies  indis- 
criminately, for  they  drink  in  oxygen,  carbonic  acid  and  water, 
but  reject  the  nitrogen. 

4.  The  fiower-leaves  are  called  petals,  and  perform  the  office 
of  inhaling  and  exhaling  various  substances;  but  they  absorb 
oxygen  at  all  times,  both  day  and  night,  and  constandy  emit 
carbonic  acid;  while,  during  the  day,  the  leaves  absorb  carbonic 
acid  and  emit  oxygen  gas,  and,  during  the  night,  reverse  the  pro- 
cess. The  flower-leaves  also  exhale  odoriferous  particles,  the 
nature  of  which,  it  is  difficult  to  determine. 

Although  plants  differ  from  animals  in  giving  no  signs  of 
perception  and  voluntary  motion,  yet  in  their  organs  and  pro- 
cesses of  nutrition  there  is  a  striking  analogy. 


60 


BIOLOGY  OF  PLANTS. 


3.  The  stem  and  branches  are  the  frame-work  or  skeleton,  for 
the  support  of  the  parts  which  are  necessary  to  the  processes 
of  nutrition. 

2.  The  roots,  in  connection  with  the  leaves,  serve  the  pur- 
poses of  mouth  and  stomach,  absorbing  and  digesting  those  sub- 
stances, which  are  held  in  solution  l)y  water  or  air. 

3.  The  common  vessels  are  tubes,  answering  to  the  lacteals  and 
veins  of  animals.  These  tubes  pass  upward  from  the  root 
through  the  stem,  and  are  distributed  in  minute  ramifications, 
over  the  surface  of  the  leaves.  Through  these  tubes  the  sap 
or  circulating  fluid  ascends. 

4.  The  leaves  are  the  lungs  which  perform  the  office  of  absorb- 
ing and  exhaling  carbonic  acid,  oxygen,  anunonia  and  water,  by 
which  the  sap  is  prepared  for  its  descent  and  assimilation. 

5.  The  proper  vessels  are  tubes  corresponding  to  the  arteries  of 
animals,  extending  from  the  leaves  through  the  inner  layer  of 
the  bark,  to  the  roots.  In  these  tubes,  the  prepared  nutriment 
descends,  yielding,  or  forming  in  its  progress,  the  peculiar  sub- 
stances which  belong  to  the  vegetable  kingdom. 

6.  Finally.  "  The  size  of  a  plant  is  proportioned  to  the  surface 
of  the  organs  which  are  destined  to  convey  food  to  it."  That  is, 
a  plant  obtains  another  mouth  and  stomach  with  every  new  fibre 
of  root,  and  every  new  leaf;  hence,  the  size  depends  upon  the 
amount  of  the  leaves  and  roots.  If  the  leaves  be  plucked  off, 
the  plant  will  either  die,  or  become  stinted  in  growth.  If  the 
roots  are  diminished,  a  similar  effect  will  be  produced.  It  is 
on  this  principle,  that  oaks  are  reared  by  Chinese  gardeners, 
both  in  Amsterdam  and  London,  only  a  foot  and  a  half  high, 
"  although  their  trunks,  bark,  leaves,  branches  and  whole  habi- 
tus evince  a  venerable  age."  As  the  leaves  and  roots  are  per- 
mitted to  increase,  they  absorb  a  greater  quantity  of  jiourish- 
ment.  This  is  not  returned  to  the  soil,  but  is  employed  in 
forming  new  organs. 

The  conditions  required  for  the  most  vigorous  action  of 
the  vital  principle,  during  the  growth  of  plants,  embrace 
nearly  the  whole  science  of  agriculture.  But  I  shall  confine 
myself,  in  this  place,  to  three  conditions ;  a  proper  medium 
and  space  in  which  to  grow,  proper  food,  and  proper  tillage. 
A  general  view  only  of  these  conditions  can  be  given  in  this 
connection,  a  more  particular  consideration  of  them  will  be 
reserved  for  future  sections. 


MEDIUM  AND  SPACE  FOR  GROWTH.  61 

I.  Proper  medium  and  space  for  groivth.  In  the  process 
of  germination,  the  only  conditions  are  air,  water,  and  a  cer- 
tain temperature.  But  as  soon  as  the  roots  and  stalks  make 
their  appearance,  they  require  mechanical  support,  and  a 
medium  for  the  action  of  those  agents  which  are  necessary  to 
their  perfect  development.  This  medium  is  the  soil  and  the 
atmosphere.  The  former  only  demands  attention  in  this 
connection.  There  are  some  aquatic  plants  that  float  upon 
the  surface  of  water  and  derive  their  nourishment  from  it,  and 
from  the  atmosphere;  and  a  large  number  of  parasitics,  as 
the  mistletoe,  which  attach  themselves  to  larger  plants  or 
trees,  and  even  to  the  rocks,  such  as  the  mosses,  from  which 
they  derive  support  and  nourishment ;  but  all  vegetables,  cul- 
tivated for  the  use  of  man,  and  other  animals,  require,  as  a 
necessary  condition  to  the  most  vigorous  action  of  their  vital 
powers,  that  their  roots  should  he  fixed  in  the  soil. 

Uses  of  the  Soil  The  soil  appears  to  serve  several  pur- 
poses in  this  respect. 

1.  It  furnishes  support  to  the  plant,  and  prevents  it  from 
being  blown  about  by  the  winds.  Different  plants  require 
different  kinds  of  soil  to  give  the  requisite  stability.  Wheat 
requires  a  stiff  soil ;  corn  a  light  one.  This  results,  not  only 
from  the  different  degrees  of  strength  in  the  vital  power,  but 
also  from  the  character  of  the  roots,  and  the  weight  which 
the  stalk  must  sustain.  Those  roots  which  lie  near  the  sur- 
face, like  most  of  our  common  grains,  require  a  stiff  soil ; 
those  which  penetrate  deep,  like  most  of  the  hoed  crops,  re- 
quire a  light  soil  in  order  to  gain  the  requisite  support ;  hence 
the  importance  of  adapting  the  crop  to  the  character  of  the 
soil,  or  the  soil  to  the  nature  of  the  root. 

2.  The  soil  is  the  repository  of  the  food  of  vegetables,  and 
a  medium  of  communicating  it  to  their  roots. 

3.  The  soil  facilitates  the  chemical  changes,  necessary  in 
the  preparation  of  the  food,  and  of  those  saline  compounds, 
which  either  act  as  a  stimulus  to  the  vital  power,  or  are  the 


63 


BIOLOGY  OF  PLANTS. 


means  of  supplying  some  other  agency  necessary  to  the  action 
of  the  vital  functions. 

•  It  has  been  suggested,  that  there  is  produced,  by  the  various 
mineral  ingredients  of  which  soils  are  mostly  composed,  an 
electrical  effect,  which  facilitates  the  absorption  of  the  food. 
The  soil,  in  connection  with  the  living  plant,  is  a  galvanic 
battery,  not  only  acting  directly  upon  the  vital  functions,  but 
also  rapidly  decomposing  the  soil  itself 

4.  The  soil  also  serves  as  a  sponge  to  retain  the  requisite 
supply  of  water.  It  retains  the  caloric,  and  permits  a  free  cir- 
culation of  air ;  all  of  which  it  distributes  according  to  the 
wants  of  the  plant. 

5.  Finally,  the  soil  serves  to  retain  gasious  proclucts,  as 
ammonia,  which  it  yields  up  as  the  wants  of  the  plant  require. 

Such  being  the  important  agency  of  the  soil,  it  is  of  the 
highest  practical  interest  to  the  farmer,  to  ascertain  its  cha- 
racter ;  for  all  soils  do  not  perform  these  functions  with  the 
same  degree  of  perfection  ;  hence  the  farmer,  before  he  casts 
the  seed  into  the  earth,  should  inquire,  whether  the  soil  is. 
fitted  to  discharge  those  duties,  which  the  peculiar  constitu- 
tion of  the  expected  crop  requires ;  and  he  should  not  hope 
for  a  bountiful  harvest,  unless  this  condition  of  the  vital  pow- 
er is  supplied.  Proper  attention  to  the  soil  is  one  of  the  se- 
crets of  successful  farming.  It  is  from  this  belief  that  I  have, 
in  future  chapters,  devoted  so  large  apart  of  the  present  work 
to  its  formation,  composition  and  improvement. 

II.  Food.  The  second  condition  required  for  the  most 
vigorous  action  of  the  vital  principle,  during  the  grov.th  of 
plants,  is  proper  food.  We  have  noticed  the  beautiful  provi- 
sion of  nature,  by  which  a  supply  of  food  is  stored  up  in  the 
seed  or  bulb,  for  the  support  of  the  germ.  This  portion,  how- 
ever, is  small,  and  when  it  is  exhausted,  food  must  be  supplied 
from  some  foreign  source,  from  the  atmosphere,  the  water, 
and  from  the  soil ;  or  the  vital  power,  having  nothing  to  act 
upon  it,  and  sustain  it,  will  be  destroyed.  Hence  proper  nour- 


FOOD  OF  PLANTS.  63 

ishment  is  equally  necessary  to  the  growth  and  perfection  of 
a  plant,  with  that  of  an  animal,  and  the  effect  of  proper  or 
improper  feeding  is  no  more  visible  in  the  one  case,  than  in 
the  other.  The  animal  and  the  plant  are  alike  dependent 
upon  foreign  matter,  not  only  for  their  growth,  but  for  exist- 
ence itself.     It  may  be  stated,  then,  as  a  general  law,  that 

All  vegetables  must  have  a  supply  of  food,  in  quantity  and 
quality,  suited  to  their  age  and  character. 

1.  The  supply  of  food  must  be  constant.  Plants  differ 
from  animals  in  this  respect ;  the  latter  require  it  at  stated 
times,  with  considerable  intervals  between  ;  while  the  former, 
owing  to  their  organs  of  nutrition,  must  have  a  constant  sup- 
ply, at  least,  during  the  period  of  growtli.  Perennial  plants, 
however,  in  cold  climates,  are  capable  of  resting  for  several 
months  without  drawing  any  nourishment  from  the  soil ;  and 
in  this  respect,  they  resemble  those  animals  which  are  torpid, 
during  the  same  period. 

2.  The  supply  of  food  must  be  properly  regulated.  If  too 
much  nourishment  is  added  at  any  one  period  of  growth,  the 
organs  will  become  clogged,  or  the  plant  will  attain  a  rapid, 
but  sickly  growth.  This  is  the  case,  when  seeds  are  planted 
in  fermenting  or  green  manures,  and  when  plants  grow  upon 
dung-hills ;  hence  the  reason  for  incorporating  the  manures 
intimately  with  the  soil.  If  too  little  food  is  supplied,  the 
plant  will  languish,  and  its  productions  will  be  scanty,  and  of 
an  inferior  quality. 

The  most  important  rule  on  this  subject  is  to  graduate  the 
nutriment,  according  to  the  wants  of  the  crop,  at  each  succes- 
sive stage  of  its  growth.  During  the  process  of  germination, 
no  foreign  matter  is  needed.  The  young  plant,  as  soon  as  its 
leaves  have  become  fully  expanded,  derives  most  of  its  matter 
from  the  atmosphere.  It  is  during  the  maturing  of  the  fruit 
or  grain,  that  plants  derive  most  nourishment  from  the  soil. 
This  is  supposed  to  be  partly  due  to  the  fact,  that  the  leaves 
and  stalks,  previous  to  the  formation  of  the  fruit,  have  their 


64  BIOLOGY  OF  PLANTS. 

organs  of  absorption  in  a  most  vigorous  state,  but,  at  that  pe- 
riod, the  pores  are  partly  closed  up,  and  the  nourishment 
must  pass  in  at  the  roots ;  and  partly  to  the  kind  of  nourish- 
ment which  the  soil  alone  is  capable  of  furnishing.  Hence, 

(1)  In  the  application  of  manures,  we  may  derive,  from 
the  above  facts,  the  most  important  practical  rules ;  the  kind 
and  quantity  depending  upon  the  time  when  the  crop  matures 
its  seeds.  If  the  crop  is  winter  rye,  or  any  of  the  smaller 
grains,  which  mature  their  seeds  in  July  or  August,  green 
manures  should  not  be  applied,  because  the  process  of  fer- 
mentation yields  abundance  of  carbonic  acid,  which  power- 
fully stimulates  and  increases  the  stalks  and  leaves,  but  is  in- 
jurious to  the  formation  of  the  grain.  This  process  will  be 
most  active  when  the  kernel  of  early  grains  is  maturing,  and 
the  appropriate  nutriment,  which  goes  to  the  seed,  will  not 
then  be  prepared  in  the  soil ;  hence  there  will  be  abundance 
of  straw,  with  but  little  grain.  But  if  the  crop  ripens  its  seed 
in  September,  like  corn  and  most  hoed  crops,  green  manures 
are  far  preferable,  because  the  fermentation  will  be  most  ac- 
tive, when  the  stalks  and  leaves  require  its  influence,  and 
the  nutriment,  which  is  formed  in  the  soil,  by  this  process, 
will  be  ready  for  the  formation  of  the  grain,  by  the  time  the 
seed  requires  it. 

(2)  The  above  facts  explain  the  reason  why  crops  exhaust 
the  soil  more  when  permitted  to  mature  their  seeds,  than  when 
cut  green  ;  hence,  crops  cut  for  fodder,  as  grass,  should  not 
be  left  to  mature  their  seeds,  in  consequence  of  their  exhaust- 
ing effects  upon  the  manures  in  the  soil ;  hence,  too,  the  utility 
of  ploughing  in  green  crops,  because  food  is  thus  taken  from 
the  atmosphere,  and  added  to  the  soil, 

(3)  Finally,  from  the  same  principle  may  be  inferred  the 
utility  of  "  soiling,"  that  is,  of  keeping  farm  stock  on  green 
crops,  during  the  summer  season.  The  green  crops,  deriving 
their  support  mostly  from  the  atmosphere,  exhaust  the  soil  but 
little,  while  their  conversion  into  manure  in  the  stables,  adds 


NATURE  OF  FOOD.  65 

directly  to  the  means  of  fertility,  of  securing  greater  abundance 
in  future  harvests. 

3.  The  kind  of  food  must  be  such  as  the  vital  forces  of  the 
plant  can  assimilate ;  such  as  lis  peculiar  constitution  requires. 
The  nature*  of  the  food  of  plants  has  been  a  subject  of  much 
conjecture  and  controversy.  Lord  Bacon  believed  it  to  be 
water  ;  Tull  and  Du  YidJueX, pulverized,  earth  ;  Hunter,  oil  and 
salt.  But  the  investigations  of  modern  chemists,  have  thrown 
much  light  on  this  subject,  although  some  things  are  not  yet 
settled.  It  now  appears,  that  the  food  of  vegetables,  like  that 
of  animals,  consists  of  several  substances  ;  that  it  is  derived 
from  numerous  sources.  The  principal  substances  regarded 
as  food,t  are  carbonic  acid,|  ammonia,  water,  and  several  or- 
ganic substances  which  form  the  constituents  of  vegetable 
mould,  and  alkalies,  alkaline  earths,  metallic  oxides  and  seve- 
ral salts. 

The  vegetable  mould,  according  to  the  analysis  of  Ber- 
zelius,  consists  of  several  compounds  of  carbon,  oxygen,  hy- 
drogen and  nitrogen,  called  humin,  humic,  crenic  and  apocre- 
nic  acids.  The  humic  acid  has  been  called  geine.  These 
substances  are  combined  in  the  soil,  in  part,  with  alkalies  and 
oxides,  and  constitute  the  principal  food  which  plants  derive 
from  that  source. 

But  different  species  of  plants  require  different  kinds  of 
food,  or  require  it  in  different  quantities.  Plants  which 
contain  a  large  quantity  of  nitrogen,  must  be  supplied  with 

*  The  full  consideration  of  this  subject  will  be  deferred  to  a  future 
section,  on  the  source  and  assimilation  of  the  simple  bodies  which  en- 
ter into  the  composition  of  plants. 

t  Nutritive  matters  are,  correctly  speaking,  those  substances  which 
when  presented  from  without,  are  capable  of  sustaining  the  life,  and 
all  the  functions  of  an  organism,  by  furnishing  to  the  different  parts^ 
of  plants,  the  materials  for  the  production  of  their  peculiar  constituents. 
— Liebig. 

X  For  a  description  of  these  bodies,  see  second  and  third  chapters. 

6 


^  BIOLOGY  OF  PLANTS. 

food  containing  that  substance,  in  a  form  in  which  they  can 
assimilate  it,  as  in  ammonia,  nitric  acid,  crenic  and  apocre- 
nic  acids.  Some  plants,  as  wheat,  require  potash  and  phos- 
phates. All  kinds  of  grasses  require  silicate  of  potash.  Sea- 
plants  require  soda.  And,  generally,  plants  require  differ- 
ent substances  to  enable  them  to  develope  their  organs.  So 
also  wheat  requires  more  alkalies  in  quantity  than  barley  or 
oats.  Saussure  found  that  wheat  requires  different  quantities 
at  different  periods  of  its  growth.  The  same  fact  has  been 
observed  of  other  plants.* 

The  absolute  necessity  of  supplying  plants  with  appropriate 
nourishment,  of  nutriment  derived  from  animal  and  vegetable 
manures,  has  been  proved,  by  the  most  carefully  conducted 
experiments,  whatever  be  the  particular  form  in  which  the 
food  is  presented,  whether  as  carbonic  acid,  water,  ammonia 
and  saline  compounds,  or,  in  addition,  as  geates  or  humates, 
crenates  and  apocrenates.  A  continued  course  of  cropping 
will  exhaust  the  soil,  both  of  vegetable  matters  and  salts,  and, 
unless  they  are  restored,  it  will  become  in  time,  wholly  bar- 
ren ;  and  in  proportion  as  these  matters  are  wanting,  or  in  a 
state  unfitted  to  enter  the  organs  of  plants,  will  the  soil  become 
sterile,  its  productions  scanty,  and  of  an  inferior  quality. 

3.  Tillage.  The  third  general  condition  necessary  to  the 
growth  of  plants,  is  proper  tillage.  The  object  of  tillage,  is 
to  break  up  the  entire  soil,  and  give  it  such  a  degree  of  fine- 
ness, as  to  render  it  permeable  to  atmospheric  agents  and  wa- 
ter, and  to  incorporate  the  manures  with  the  soil ;  thus  to  pro- 
mote an  equal  and  economical  distribution  of  food  to  the  roots 
of  plants  ;  to  bury  the  seed  at  the  proper  depth  ;  and  finally,  to 
destroy  weeds,  which  rob  the  crop  of  food,  and  check  its 
growth. 

( 1 )  The  soil  should  be  thoroughly  'ploughed ;  every  part  of  it 
turned  over  and  stirred  at  a  sufficient  depth  to  allow  the  roots 
of  plants  to  extend  themselves  freely  in  every  direction.     If 

*  For  a  further  notice  of  this  subject,  see  third  chapter. 


PROPER  TILLAGE  67 

this  is  not  done,  if  the  furrow  is  wider  than  the  plough  can 
turn,  the  parts  not  broken  up  will  obstruct  the  roots,  and  pre- 
vent the  free  circulation  of  air  and  water.  The  water,  set- 
tling in  the  creases  of  the  furrows  on  the  sub-soil,  will  form  al- 
ternate wet  and  dry  ridges,  which  will  injure  the  delicate  parts 
of  the  roots.  When  the  soil  is  only  partly  broken,  but  a  small 
part  of  it  is  brought  to  bear  upon  the  roots,  and  hence  the 
nourishment  is  withheld  from  the  crop. 

(2)  The  soil  should  he  deeply  ploughed.  This  is  especially 
necessary  for  root  crops,  and  highly  useful  for  any  crop,  pro- 
vided sufficient  manure  is  added.  Ten  inches  of  tillage  depth 
are  far  preferable  to  six  inches,  because  the  former  depth  will 
keep  the  soil  drier,  and  render  it  capable  of  being  cultivated 
much  earlier.  Such  a  depth  renders  the  soil  less  subject  to 
drought,  in  consequence  of  furnishing  a  larger  stratum,  pos- 
sessing the  properties  of  a  sponge,  to  absorb  the  water  and  re- 
tain it  for  the  wants  of  the  plant.  Such  a  soil  will  be  a  better  re- 
tainer of  heat ;  and  will  furnish  a  better  medium  for  the  ac- 
tion of  chemical  and  other  agents,  which  are  necessary  to  the 
most  vigorous  growth  of  vegetables. 

The  experiments  of  Baron  Von  Vought,  upon  the  estate 
of  Flottbeck,  Germany,  fully  establishes  the  utility  of  deep  til- 
lage. After  making  thousands  of  experiments  during  thirteen 
years,  he  came  to  the  conclusion,  that  a  tillage  depth  of  from 
ten  to  fourteen  inches  was  vastly  preferable  to  a  less  depth. 
And  Von  Thaer  estimates  the  value  of  soils,  with  a  flat  and 
deep  mould,  in  the  following  proportions.  If  with  a  cultiva- 
ted soil  three  inches  in  depth,  the  land  is  worth  thirty-eight 
dollars  per  acre,  that  of  five  inches  will  be  worth  fifty-six  dol- 
lars ;  that  of  eight  inches  will  be  worth  sixty-two  dollars,  and 
that  of  eleven  inches,  seventy-four  dollars.  Each  inch  of 
mould  between  six  and  ten  inches,  increases  the  value  eight 
per  cent. 

The  importance  of  deep  tillage  may  be  inferred,  from  the 
fact,  that  some  plants,  as  lucerne  and  sainfoin,  are  said  to  have 


OO  BIOLOGY  OF  PLANTS. 

penetrated  the  soil,  to  a  depth  of  thirty  feet,  and  that  the  tap 
roots  of  clover  and  some  other  plants  extend  to  a  depth  of 
three  feet  or  more. 

(3)  The  soil  should  be  finely  pulverized;  especially  the 
surface  to  the  depth  of  six  inches ;  in  order  that  the  seed  corn, 
grain,  or  potato  shoot  may  be  placed  in  earth  finely  divided, 
into  which  the  tender  fibres  of  the  root  may  easily  and  quick- 
ly shoot,  and  air,  water  and  heat  operate  with  facility. 

If  the  soil  is  lumpy,  large  pores  or  intervals  will  exist, 
across  which,  the  delicate  fibres  of  the  roots  will  extend  them- 
selves, become  exposed  to  injury,  and  unable  to  discharge 
their  functions  in  a  vigorous  manner. 

Professor  Hitchcock  accounts  for  the  superior  fertility  of 
the  alluvial  soils  of  New  England,  on  this  principle.  Such 
soils  do  not  contain  so  large  a  quantity  of  vegetable  matter  as 
those  less  fertile,  but  their  materials  are  in  a  much  more  fine- 
ly divided  state,  and  hence  their  fertility.  This  condition 
of  vitality  is  liable  to  be  disregarded  by  the  farmer,  because 
the  expense  of  preparing  the  soil,  in  the  first  instance,  is  much 
increased,  and  because  the  time  of  sowing  and  of  harvesting, 
are  too  far  removed  to  impress  the  mind  with  its  necessity 
and  utility,     i  c  j 

(4)  The. soil  should  he  covered  at  the  proper  depth.  The 
requisite  depth  varies  according  to  the  nature  of  the  seed,  but 
generally  the  smoother  and  finer  the  surface,  the  less  the  depth 
required.  Grain  covered  one  fourth  of  an  inch  in  depth  by 
finely  pulverized  earth,  where  it  will  feel  the  influence  of  heat, 
moisture  and  air  combined,  will  be  much  more  likely  to  ger- 
minate, the  vitality  will  be  much  sooner  excited,  the  roots 
will  become  more  powerful  and  the  stalks,  leaves  and  fruit 
much  more  abundant. 

The  Baron  Von  Vought  has  made  a  numerous  collection  of 
plants,  in  which  the  seed  was,  in  the  one  case,  covered  only 
two  lines  in  depth,  and  in  the  other  a  little  more  than  one  inch 
and  a  half ;  and  these  plants  show,  "  what  a  striking  differ- 


PROPER  TILLAGE.  O^ 

ence  there  is  in  the  vital  germ  lying  on  the  surface  where 
roots  and  leaves,  immediately,  numerously  and  powerfully 
shoot  forth  from  one  point,  and  the  weakened  vital  germ,  ly- 
ing at  the  depth  of  1.680  inches,  shoots  forth  few  roots,  but  a 
thin  tube,  which  rises  as  far  as  the  surface,  where  a  knot  is 
formed  whence  the  weakened  germ  pushes  forth  a  single  and 
sickly  plant." 

Some  seeds  require  to  be  covered  only  by  a  bush-harrow. 
The  seeds  of  grain-crops,  and  of  some  garden  vegetables  may 
be  covered  in  this  way,  but  hoed  crops  require  a  greater  depth. 
The  requisite  depth  depends  also  on  other  circumstances — 
the  character  of  the  soil,  and  its  state  of  moisture  or  dryness. 
Hence  farmers  should  adapt  their  mode  of  tillage  to  these  cir- 
cumstances, if  they  would  derive  the  highest  benefit  from  this 
part  of  culture. 

(5)  Finally.  The  soil  should  be  kept  free  of  weeds.  The 
reason  for  this  is,  that  the  weeds  exhaust  the  soil  as  much  as, 
if  not  more  than  the  crop,  and  especially  in  the  dry  season,  ab- 
stract from  the  soil  the  moisture  required  for  the  grain.  In  this 
latter  respect,  weeds  with  large  leaves  and  stems,  will  take  up 
through  their  roots  and  transpire  through  their  leaves,  their 
weight  of  moisture  in  twenty-four  hours.  The  vital  functions 
of  the  crop  are  thus  enfeebled  or  destroyed,  while  the  ruthless 
weeds  fatten  upon  the  provisions  which  were  designed  for  the 
rightful  inhabitants  of  the  soil.  There  is  no  doubt  but  that 
many  a  crop  has  been  diminished  one  quarter,  one  third  and 
even  one  half  by  the  weeds  which  have  been  allowed  to  seed 
and  spread  themselves  on  the  land. 

The  conditions  of  the  growth  of  plants  as  presented  in  this 
section  are  very  general,  they  will  be  more  fully  expanded 
in  succeeding  parts  of  the  work. 

These  general  conditions  of  life,  however,  should  be  im- 
pressed upon  the  mind  of  every  farmer,  if  he  would  aid  the 
vital  power  in  the  growth  of  his  crops.  He  must  supply  his 
plants  with  the  proper  medium  and  support ;  with  soil  fitted 

6* 


70  BIOLOGY  OF  PLANTS. 

to  the  nature  of  the  plant;  with  food,  in  kind  and  quantity ^ 
suited  to  the  age  and  wants  of  each  species,  and  with  proper 
tillage.  Especially  must  he  exterminate  those  natural  foes, 
which  make  their  appearance  during  the  summer  months,  and 
which  may  easily  be  overcome  if  attacked  before  they  have 
obtained  a  firm  footing  on  the  soil ;  but  let  him  remember, 
that  they  possess  a  wonderful  fecundity,  and,  like  a  certain 
animal,  have  many  lives,  they  must,  therefore,  be  made  to  die 
many  deaths,  before  they  can  be  completely  exterminated. 

The  importance  of  supplying  the  conditions,  for  exciting 
the  vital  principle  of  seeds,  and  for  its  most  perfect  action 
during  the  growth  of  plants,  may  be  illustrated  by  reference 
to  the  mechanic  arts.  In  all  these  arts  there  is  some  agent, 
natural  or  artificial,  employed  as  a  moving  power. 

1.  In  locomotives  and  steamboats,  the  main  spring  of  the 
whole  movement  is  the  expansive  force  of  steam,  when  sub. 
jected  to  a  high  temperature.  But  steam  has  no  power  unless 
supplied  with  the  appropriate  conditions.  If  made  in  the  open 
air  it  will  not  move  a  steamboat,  though  it  may  a  feather.  If 
simply  confined  in  a  boiler,  it  will  manifest  its  power  in  no  way 
unless  it  be  to  break  from  its  confinement,  and  gain  its  free- 
dom. A  complicated  apparatus  must  be  supplied,  the  result 
of  intense  study,  and  multiplied  experiment,  before  its  power 
is  available  for  any  useful  purpose ;  and  finally,  various  other 
conditions  must  be  added,  before  it  will  propel  us  across  the 
land  or  the  ocean. 

2.  In  most  cotton  and  woollen  factories  the  moving  force  is 
water.  This  power  also  requires  several  conditions,  before 
it  can  be  usefully  applied.  The  force  of  running  water, 
though  often  very  great,  will  not  manufacture  cotton  and  wool- 
len cloths.  If  it  is  arrested  in  its  progress  to  the  ocean,  its 
force  will  only  be  exerted  upon  the  sides  of  the  dam.  Fac- 
tories must  be  erected,  wheels  of  the  proper  size  and  form 
must  be  constructed.  There  must  be  added  a  complicated 
apparatus  of  cards,  spindles  and  looms,  and  after  all  this,  cot- 


VITAL  AND  PHYSICAL  AGENTS.  71 

ton  or  wool  must  be  supplied,  and  workmen  who  understand 
the  operation  of  the  machinery,  before  the  beautiful  fabric  is 
wrought  and  fitted  to  adorn  our  bodies,  or  to  protect  them 
from  the  vicissitudes  of  the  seasons. 

Steam  and  water  are  the  great  agents  in  these  processes, 
but  they  are  not  the  only  agents,  nor  will  they  avail  us  unless 
the  necessary  conditions  are  supplied. 

The  vital  power  is  much  more  wonderful  and  useful  in  its 
operations,  than  any  of  the  agents  of  dead  matter  ;  but  it  will 
not  exert  its  force  without  its  conditions,  any  more  than  steam 
and  water.  When  its  conditions  of  activity  are  supplied,  its 
productions  in  their  variety,  beauty  and  utility,  exceed  those 
of  all  other  agents  of  the  natural  world.  This  power  supplies 
the  manufacturing  arts  with  nearly  all  their  raw  material,  and 
is  emphatically  the  sustaining  cause,  in  the  hand  of  the  Deity, 
of  the  present  order  of  nature. 

If  it  is  important,  then,  that  the  mechanic  and  artizan  should 
spend  years  of  study  and  labor  to  supply  the  necessary  con- 
ditions for  the  exertion  of  steam  and  water  power,  is  it  not 
vastly  more  important,  that  the  farmer  should  carefully  study, 
and  faithfully  supply  the  appropriate  conditions  for  the  exer- 
cise of  the  vital  power,  that  he  may  avail  himself  of  its  more 
valuable  and  indispensable  productions.  What  engineer  would 
expect  to  run  steamboats  and  locomotives,  with  nothing  but 
fire  and  water  ?  What  manufacturer  could  hope  to  spin  and 
weave  by  the  mere  force  of  hydrostatic  pressure  ?  Or  what 
mechanic  of  any  trade,  would  expect  to  produce  a  beautiful 
and  useful  material,  without  carefully  attending  to  the  condi- 
tions which  are  required  for  its  production  ?  Why,  then, 
should  the  farmer  expect  a  bountiful  harvest,  if  he  neglect  to 
supply  the  conditions  required  for  the  activity  of  the  vital 
power  in  the  production  of  his  crops  ? 

In  agriculture,  as  in  the  mechanic  arts,  we  need  the  influ- 
ence of  example.  We  need  some  few  farmers,  in  every  portion 
of  the  country,  who  shall  present  living  examples  to  all  around, 


72  BIOLOGY  OF  PLANTS. 

of  the  possibility  and  utility  of  supplying  these  conditions  of 
vegetable  life. 

It  is  on  this  account  that  I  would  urge  upon  the  young  far- 
mer to  study  this  subject,  to  obtain  a  scientific  knowledge  of 
it,  that  he  may  be  able  to  exhibit  a  practical  application  of  the 
principles  here  suggested,  when  he  settles  down  to  the  great 
business  of  life. 


CHAPTER  II. 

INFLUENCE  OF  THE  ATMOSPHERE,  WATER  AND  OTHER 
AGENTS  UPON  THE  VITAL  PRINCIPLE  AS  CONNECTED 
WITH    THE    PHENOMENA    OF    VEGETATION. 

Some  of  these  agents  have  already  been  alluded  to  when 
treating  of  the  vital  principle,  considered  as  the  principal 
cause  of  vegetable  productions.  It  is  proposed  now  to  con- 
sider more  particularly  the  degree  in  which  they  favor  or  re- 
tard the  process  of  nutrition,  with  the  mode  in  which  they  act, 
in  order  more  fully  to  explain  the  philosophy  of  the  subject, 
and  to  point  out  suitable  methods,  to  be  employed  by  the  ag- 
riculturist in  the  culture  of  his  crops.  These  agents  are 
the  atmosphere,  water,  gravity,  cohesion,  affinity,  heat,  light, 
electricity,  and  the  agency  of  man. 

Sect.  1.  Agency  of  the  Atmosphere. 

The  atmosphere  is  that  gaseous  fluid  which  surrounds  the 
earth,  and  extends  to  a  distance  of  forty  or  forty-five  miles 
above  it.  It  is  composed  essentially  of  oxygen  and  nitrogen 
in  the  proportion  of  21  parts  of  the  former,  to  79  of  the  latter 
in  100.  The  atmosphere  also  contains  variable  quantities  of 
watery  vapors,  ytj^uiy  part  by  volume  of  carbonic  acid,  a 
smaller  quantity  of  ammonia,  and  several  other  gaseous  com- 


INFLUENCE  OF  THE  ATMOSPHERE.  73 

pounds,  such  as  hydrogen,  nitric  acids,  sulphureted  and  car- 
bureted hydrogen.  It  is  also  probable  that  odoriferous,  sa- 
line, and  metallic  particles  float  in  it ;  all  of  which,  save  the 
first,  are  found  in  exceedingly  small  quantities.  The  agency 
of  the  atmosphere  may  be  studied  under  the  following  heads. 
Influence  of  its  oxygen,  of  its  nitrogen,  of  its  ammonia,  of  its 
nitric  acid,  of  its  sulphureted  hydrogen,  of  its  carbonic  acid, 
and  its  mechanical  agency. 

I.  Injluence  of  the  oxygen  of  the  air  in  vegetation.  We 
have  seen,  that  oxygen  is  a  most  important  agent  in  the  pro- 
cess of  germination,  combining  with  the  hydrogen  of  the  de- 
composed water,  and  with  the  carbon  of  the  seed,  and  that 
carbonic  acid  is  almost  the  only  gaseous  product  evolved. 

Oxygen  is  no  less  necessary  to  the  growth  of  plants. 
This  is  proved  by  the  fact,  that  when  all  other  conditions  are 
supplied,  if  the  plant  is  deprived  of  oxygen  it  will  wither  and 
die ;  hence,  when  the  roots  of  trees  are  surrounded  with 
stagnant  water,  no  oxygen  being  supplied  to  them,  the  leaves 
turn  yellow  and  fall,  but  when  fresh  water  is  added,  yielding 
the  requisite  quantity  of  oxygen,  the  tree  will  revive. 

Oxygen  acts  principally  upon  the  roots  and  leaves  oi plants- 
The  mode  of  its  action  in  the  roots  has  been  differently  rep- 
resented by  different  chemists.  There  are  four  theories.  1. 
The  absorbed  oxygen  combines  with  the  carbon  of  the  plant. 

2.  It  combines  with  the  hydrogen  of  the  decomposed  water. 

3.  It  is  assimilated.  4.  It  combines  with  substances  in  the 
soil  by  which  food  is  prepared. 

First  theory.  The  roots  absorb  oxygen  and  convert  it  by 
means  of  their  carbon  into  carbonic  acid.  The  truth  of  this 
theory  is  supposed  to  be  proved  by  placing  fresh  roots  depri- 
ved of  their  stems  under  a  bell-glass  receiver.  They  will  di- 
minish the  quantity  of  air,  by  abstracting  its  oxygen,  and 
forming  carbonic  acid.  The  volume  of  oxygen  consumed  is 
never  greater  than  the  bulk  of  their  roots. 

Place  the  roots  thus  saturated  with  oxygen  in  a  receiver 


74  BIOLOGY  OF  PLANTS. 

of  air,  and  carbonic  acid  will  be  given  off  without  altering 
the  volume  of  the  air  ;  but  if  they  are  placed  in  the  open  air, 
they  will  absorb  a  volume  of  oxygen  equal  to  themselves,  as 
in  the  first  instance  ;  hence,  the  atmosphere  abstracts  the 
carbonic  acid  which  the  roots  form.* 

If  the  roots  are  connected  with  the  stems  and  leaves,  they 
will  constantly  absorb  oxygen,  and  the  quantity  will  amount, 
in  time,  to  much  more  than  their  volume,  because  the  carbon- 
ic acid  which  they  form  passes  into  the  juices,  ascends  to  the 
leaves,  where  it  is  decomposed  by  the  action  of  light,  or  tran- 
spired with  the  water,  if  the  plant  is  in  the  shade  ;  hence,  they 
never  become  saturated.  But  these  facts  are  equally  well  ac- 
counted for  on  other  theories. 

Second  theory.  The  oxygen  of  the  air,  which  is  absorbed 
by  the  roots,  combines  with  the  hydrogen  of  the  water,  which 
the  vital  power  decomposes,  while  the  oxygen  of  the  decompo- 
sed water  combines  with  carbon  and  forms  carbonic  acid ; 
hence,  the  agency  of  the  oxygen  of  the  air  is  to  keep  up  the 
supply  of  water. 

Third  theory.  The  oxygen  thus  absorbed  by  the  roots,  is 
directly  assimilated  to  the  vegetable  products,  or,  if  any  chan- 
ges take  place,  the  oxygen  is  neither  converted  into  carbon- 
ic acid  by  combining  with  the  carbon,  nor  into  water  by  unit- 
ing with  the  hydrogen  of  the  decomposed  water.  These 
changes  may  take  place,  but  the  theory  supposes  that  the  oxy- 
gen in  some  forin  is  assimilated  to  the  vegetable  organs. 

Fourth  theory.  It  is  possible,  however,  that  neither  of 
the  above  theories  explain  the  reason  of  the  necessity  of  oxy- 
gen to  the  roots  of  plants,  in  order  to  promote  their  growth. 
The  oxygen  of  the  air  effects  changes  upon  the  humus  of  the 
soil,  in  preparing  the  food,  and  this  may  be  the  reason  for  its 
influence. 

But  whatever  view  is  taken,  the  agency  of  oxygen  upon 
the  roots  of  plants,  explains  the  reason  why  the  earth  must  be 

^  Chaptal. 


INFLUENCE  OF  THE  ATMOSPHERE.  75 

Stirred  about  them.  The  oxygen  of  the  air  is  thus  either 
brought  into  direct  contact  with  all  parts  of  them,  so  as  to 
answer  the  conditions  of  some  one  of  the  above  theories,  or 
else  it  is  thus  brought  into  contact  with  the  humus,  and  pro- 
motes its  decay  and  conversion  into  vegetable  food. 

The  leaves  of  plants  also  absorb  oxygen  from  the  atmos- 
phere, especially  during  the  night  season,  and  sometimes  in 
the  shade,  at  the  same  time  they  transpire  carbonic  acid,  and 
the  volume  of  carbonic  acid  thrown  off,  is  just  equal  to  that 
of  the  oxygen  consumed.  The  changes  which  take  place  in 
this  process  are  also  subjects  of  theory,  although  it  is  pretty 
well  established  that  the  last  of  the  three  following  is  the  true 
one. 

First  theory.  The  oxygen,  absorbed  by  the  leaves,  enters 
into  combination  with  the  carbon,  formerly  introduced  into 
the  sap  of  the  plant,  and  there  being  no  light  to  decompose 
the  carbonic  acid  thus  formed,  it  is  exhaled,  or  given  back  to 
the  atmosphere.  This  is  precisely  the  change,  which  is  sup- 
posed by  some  to  take  place  in  the  lungs  of  animals,  and  is 
a  true  process  of  respiration.  Some  of  the  oxygen  however 
must  remain  uncombined  in  the  juices,  as  the  amount  of 
Jg  part  of  the  quantity  absorbed  can  be  disengaged  from  the 
plant  by  means  of  heat. 

Second  theory.  The  oxygen  which  is  absorbed  by  the 
leaves,  enters  into  combination  with  the  hydrogen  of  the  wa- 
ter which  the  vital  power  decomposes,  in  the  same  manner 
as  when  introduced  into  the  roots.  So  that  water  is  decom- 
posed by  the  plant,  its  oxygen  assimilated,  while  at  the  same 
time,  the  hydrogen  combines  with  the  absorbed  oxygen,  and 
forms  water.  This,  however,  is  a  very  doubtful  theory  of 
these  changes,  though  a  possible  one. 

Third  theory.  The  oxygen  thus  absorbed,  combines  with 
the  vegetable  substances  in  the  leaves.  This  appears  to  be  a 
purely  chemical  process,  as  it  takes  place  equally  well  in  the 
dead,  as  in  the  living  plant.     If  the  substance  of  the  leaves 


76  BIOLOGY  OF  PLANTS. 

is  known,  "  it  is  a  matter  of  the  greatest  ease  and  certainty  to 
calculate  which  of  them,  during  life,  should  absorb  most 
oxygen  by  chemical  action  when  the  influence  of  light  is 
withdrawn."  The  oxygen  in  this  casecombines  with  the  vol- 
atile oils,  and  changes  them  into  resins,  in  some  cases,  while 
in  others,  it  unites  with  the  constituents  of  nut-galls,  and 
forms  acids,  or  with  substances  containing  nitrogen. 

The  carbonic  acid  in  this  case  is  derived  from  the  sap  ;  it 
enters  the  roots  with  the  water,  and  when  it  arrives  at  the 
leaves  it  is  not  decomposed,  but  is  transpired  along  with  the 
water  ;  this,  of  course,  is  purely  a  mechanical  process,  and 
the  quantity  of  acid  will  depend  on  the  quantity  of  water. 
The  absorption  of  the  oxygen  and  the  emission  of  carbon- 
ic acid  have  no  connection  therefore  with  each  other,  or 
with  the  process  of  assimilation.  A  cotton  wick,  in  a 
lamp  filled  with  water,  saturated  with  carbonic  acid,  acts  pre- 
cisely like  a  plant  in  the  night ;  water  and  carbonic  acid  are 
sucked  up,  and  evaporated  from  the  wick. 

The  quantity  of  oxygen  absorbed  by  plants  depends  upon 
their  vigor,  degree  of  heat,  and  the  nature  of  their  leaves. 

1.  The  more  vigorous  the  plant  is,  the  greater  the  quantity 
of  oxygen  which  it  is  capable  of  absorbing  during  any  given 
period.  This  we  should  expect,  because  all  the  vital  forces 
are  more  active,  and  hence  the  growth  must  be  more  rapid, 
and  require  a  larger  supply  of  the  appropriate  nutriment. 

2.  The  same  species  of  plants  will  absorb  more  oxygen  at 
a  temperature  of  88°  F.  than  at  55°  or  56°  F.*  This  quan- 
tity will  therefore  depend  upon  the  season  of  the  year  and 
upon  the  climate. 

3.  The  leaves  of  different  plants  do  not  consume  the  same 
quantity  of  oxygen  gas,  at  the  same  temperature,  and  seasons 
of  the  year.  The  quantity  varies  from  a  little  more  than  one 
half  the  bulk  of  the  leaves,  to  eight  times  their  volume. 

The  fleshy-leaved  plants  absorb  the  least  oxygen,  and  re- 

*  Chaptal. 


INFLUENCE  OF  THE  ATMOSPHERE.  77 

tain  it  with  great  force,  (probably  because  they  emit  little  or 
no  carbonic  acid).  The  various  species  of  these  plants,  ac- 
cording to  the  experiments  of  Saussure,  absorb  during  the 
summer  months,  jfrom  1  to  1.7  of  their  bulk  of  oxygen  ;  hence, 
such  plants  will  flourish  on  high  mountains,  where  the  air  is 
rarified,  and  on  arid  sands. 

The  leaves  of  evergreen  trees  are  next  in  order,  as  they  ab- 
sorb more  oxygen  than  the  fleshy-leaved  plants,  and  much 
less  than  those  trees  which  lose  their  leaves  during  the  win- 
ter. The  quantity  in  this  class,  varies  during  the  months  of 
May  and  June  from  1.5  to  four  times  their  volume,  and  dur- 
ing the  month  of  September  from  0.86  to  3  times  their 
volume.* 

Of  the  herbaceous  plants^  those  which  grow  on  marsh- 
es and  bogs,  absorb  but  little  oxygen  gas.  This  may  be 
due  to  the  fact,  that  they  are  surrounded  by  an  atmosphere 
of  vapor,  or  of  carbonic  acid,  which  does  not  render  the  in- 
troduction of  oxygen  necessary.  The  quantity  in  such  plants 
under  similar  circumstances  varies  from  0.7  to  2.3  times 
the  volume  of  the  leaves,  while  the  leaves  of  herbaceous 
plants  not  aquatic,  absorb  from  0.66  to  5  times  their  vol- 
ume. 

The  leaves  of  those  trees  which  are  nailed  during  the  win- 
ter, as  the  oak,  maple,  and  most  fruit  trees,  absorb  the  larg- 
est quantity  of  oxygen,  and  contain  the  most  carbon.  This 
seems  to  depend  upon  the  nature  of  the  substances  formed  in 
the  leaf;  thus  the  tasteless  leaves  of  the  Agave  Americana  ab- 
sorb only  0.3  of  their  volume  in  the  dark  during  twenty-four 
hours;  those  of  the  oak  containing  tannic  acid,  fourteen 
times  as  much  ;  and  the  balmy  leaves  of  the  poplus  alba  twen- 
ty-one times  that  quantity.  The  large  quantity  of  oxygen, 
absorbed  by  these  plants,  may,  also,  be  partly  due  to  the  fact, 
that  they  not  only  supply  nourishment  for  the  purposes  of  veg- 


Thompson's  Chemistry,  Organic  bodies,  p.  999. 

7 


BIOLOGY  OF  PLANTS. 


etation  during  the  summer,  but  store  up  large  quantities  for 
the  use  of  the  plant,  before  it  can  derive  it  from  a  foreign 
source  in  the  spring.  This  process  has  been  compared  to 
torpidity  in  certain  animals,  which  store  up  a  quantity  of  fat 
in  the  autumn,  from  which  they  are  nourished  during  their 
winter  slumbers.  But  the  analogy  is  very  slight,  while  the 
chemical  changes  are  quite  different.  The  fat  in  the  animal, 
appears  to  combine  with  the  oxygen  in  the  lungs,  a  process 
resembling  the  burning  of  a  candle,  by  which  the  fat  is  slow- 
ly consumed ;  but  the  starch,  which  is  laid  up  in  the  organs 
of  the  tree,  is  converted  into  sugar,  and  in  the  spring  is  as- 
similated. The  process  of  assimilation  is  only  delayed,  until 
the  leaves  are  put  forth,  while  in  animals,  no  assimilation  of 
the  stored  matter  takes  place  ;  it  simply  burns  out. 

The  quantity  of  oxygen  absorbed  in  all  these  cases  must 
also  depend  upon  the  fertility  of  the  soil,  and  the  quantity  of 
the  gas  contained  in  the  air  by  which  the  plant  is  surrounded. 

The  other  parts  of  plants,  such  as  the  wood,  petals,  and 
all  those  parts  which  are  not  green,  absorb  but  a  small  quanti- 
ty of  this  gas  which  is  generally  retained. 

The  action  of  oxygen,  according  to  the  experiments  of 
Saussure,  upon  the  fruit,  during  the  progress  of  growth,  is  pre- 
cisely similar  to  that  upon  the  leaves.  Fruits  absorb  oxygen 
during  the  night,  and  give  it  off  during  the  day.  But  the  ex- 
periments of  Berard  seem  to  indicate  a  different  process,  during 
the  ripening  of  fruits ;  oxygen  being  absorbed,  and  carbonic 
acid  given  off,  both  in  the  sun,  and  in  the  shade.  This  is 
doubtless  true  ;  for  it  is  found,  that  green  fruits,  fully  grown, 
will  not  ripen  in  atmosphere  deprived  of  oxygen,  but  will  com- 
mence the  process  on  its  admission,  provided  they  do  not  re- 
main deprived  of  it  too  long.  Hence  fruits  may  be  preserved 
through  the  year,  by  surrounding  them  with  an  atmosphere  of 
carbonic  acid,  or  by  excluding  the  air.  By  the  process  of  ri- 
pening, the  animal  matter,  woody  fibre,  malic  acid  and  water, 
are  diminished,  and  the  sugar  is  increased.     This  would  be 


AGENCY  OF  OXYGEN.  79 

the  effect  of  absorbing  oxygen,  and  giving  out  carbonic  acid. 
When  the  fruit  decays,  it  gives  out  large  quantities  of  car- 
bonic acid.  The  carbon  is  furnished  by  the  substance  of  the 
fruit,  the  oxygen  from  the  decomposition  of  water  ;  the  same 
changes  which  take  place  in  the  decay  of  woody  fibre,  or  any 
other  vegetable  body. 

From  this  view  it  appears,  that  the  principal  agency  of  the 
oxygen  of  the  air  in  the  process  of  nutrition  is, 

1.  According  to  the  views  of  Thompson  and  ether  chemists, 
to  combine  with  carbon,  and  form  carbonic  acid.  This  change 
takes  place  both  in  the  soil,  and  in  the  living  plant.  In  the 
soil,  mostly  by  the  fermentation  of  manures,  or  vegetable  sub- 
stances ;  and  in  the  tree,  by  uniting  with  the  carbon  which 
has  been  previously  introduced,  forming  carbonic  acid ;  this 
with  that  contained  in  the  soil  and  air,  and  which  enters  the 
vegetable  organs  \u  solution,  is  conveyed  to  the  leaves,  and 
decomposed  by  the  influence  of  light ;  the  carbon  being  re- 
tained or  assimilated,  and  the  oxygen  sent  out  to  combine 
with  fresh  portions  of  carbon,  ready  again  to  pass  through  the 
same  process. 

The  oxygen  which  is  absorbed  by  the  leaves  and  roots,  is, 
for  the  m.ost  part,  transpired  into  the  atmosphere  ;  but  a  part 
is  retained,  and  aids  still  farther,  by  its  various  combinations, 
the  growth  and  perfection  of  the  plant.     Or, 

2.  According  to  Liebig,  the  oxygen  of  the  air  combines 
with  the  vegetable  products,  by  Rpurelt/  chemical  process,  and 
aids  the  plant  in  the  formation  of  several  vegetable  bodies, 
while  the  oxygen  which  plants  emit  is  derived  from  water 
and  carbonic  acid,  which  are  decomposed  in  the  process  of 
assimilation.  This  is  the  more  probable  theory.  But  what- 
ever view  we  take  of  it,  whether  the  oxygen  is  derived  from 
the  air,  or  the  water ;  whether  it  combines  in  the  vegetable 
organs  with  carbon,  or  is  directly  assimilated,  it  appears  to  be 
an  indispensable,  but  subordinate  agent,  to  the  vital  power, 
forming,  by  its  combinations,  those  compounds  which  this 


80  BIOLOGY  OP  PLANTS. 

power  uses  for  the  purposes  of  the  vegetable  economy ;  and 
yet,  so  controlled  by  it  as  to  change  the  order  of  its  affinities, 
and  the  character  of  the  substances,  of  which  it  forms  a  part, 
in  the  vegetable  kingdom. 

Oxygen  exerts  an  equally  important  agency  upon  soils  and 
manures,  combining  with  the  metals,  and  forming  oxides  and 
acids,  which,  by  their  union,  compose  the  soil ;  and  effecting 
changes  in  the  vegetable  matter  of  the  soil,  especially  con- 
verting insoluble  into  soluble  food.  This  agency  will  be  fur- 
ther illustrated  in  a  future  section. 

II.  Influence  of  the  Nitrogen  of  the  Air.  All  plants,  in  some 
of  their  organs,  contain  nitrogen  in  combination  with  other 
substances,  but  do  not  probably  derive  it  directly  from  the  at- 
mosphere. Although  nitrogen  seems  necessary  to  the  process 
of  vegetation,  we  do  not  know  what  agency  that  which  is 
contained  in  the  air  exerts,  unless  it  acts,  simply,  as  a  dilu- 
ent to  the  oxygen.  A  small  quantity  of  nitrogen  is  absorbed 
by  the  organs  of  plants,  and  given  out  again  in  an  unaltered 
state. 

III.  Ammonia  of  the  Atmosphere.  That  the  atmosphere 
contained  ammonia,  in  small  quantities,  every  chemist  well 
knew ;  but  it  was  first  proved,  beyond  a  doubt,  by  Liebig, 
who  has  calculated  its  probable  amount,  both  in  the  air,  and 
in  rain  water.  A  pound  of  the  latter  contains  from  one  quarter 
to  one  grain  of  this  gas.  Hence  there  would  fall,  on  the  sur- 
face of  an  acre,  more  than  eighty  pounds  of  ammonia,  annually. 
The  ammonia  of  the  atmosphere,  owing  to  its  great  solubil- 
ity, is  brought  to  the  earth  by  every  shower  of  rain,  and  h^ce 
must  enter  the  organs  of  plants. 

Ammonia  is  also  found  in  the  soil,  in  clays,  in  oxide  of 
iron,  and  in  several  other  bodies,  which  must  have  derived  it 
from  the  atmosphere.  Liebig  and  Dr.  Wilbrand  found  it  in 
maple  sap,  the  juice  of  the  birch,  and  of  beet  root.  How  is  the 
atmosphere  supplied  with  this  substance  ?  This  question  is 
easily  answered  by  reference  to  changes  in  progress  on  the 
surface  of  the  earth. 


AMMONIA  OF  THE  ATMOSPHERE.  81 

1.  TJie  putrefaction  of  animal  substances  is  always  attend- 
ed by  the  revolution  of  ammonia,  as  a  gaseous  product.  The 
nitrogen  which  animals  contain,  is  separated,  mostly,  in  this 
form.*  In  the  decay  of  plants  also,  ammonia  is  given  off. 
The  quantity  thus  formed,  is  very  great.  "  A  generation  of 
a  thousand  million  men  is  renewed  every  thirty  years,  thou- 
sands of  millions  of  animals  cease  to  live,  and  are  reproduced 
in  a  much  shorter  period." 

The  ammonia,  thus  produced,  is  partly  thrown  off  into  the 
atmosphere,  and  partly  retained  in  the  soil  in  the  form  of 
salts,  or  condensed  in  the  pores  of  the  humus,  clay,  water,  or 
other  ingredients  of  the  soil.  Some  of  it  enters  the  roots  of 
plants,  a  large  portion  is  washed  into  the  sea  by  rivers,  or 
carried  there  in  rains.  A  part  of  that  which  remains  in  the 
atmosphere  is  liable  to  be  decomposed  by  thunder  storms,  so 
that  but  a  small  quantity  of  that  which  is  derived  from  this 
source,  exerts  any  agency  upon  vegetation. 

2.  When  vegetable  substances  which  contain  no  nitrogen 
decay  or  are  oxidized  in  the  open  air,  they  exert  a  catalytic 
force  upon  the  nitrogen  of  the  atmosphere  and  the  hydrogen 
of  the  plant,  and  ammonia  is  formed  in  considerable  quantities. 

In  a  similar  way,  also,  when  inorganic  substances  suffer 
oxidation  in  air  or  water,  ammonia  is  formed  ;  thus  Faraday 
found,  that  when  oxides  were  decomposed  by  potassium  in  the 
air,  this  gas  was  evolved ;  and  Chevalier  produced  it  by  ex- 
posing moist  iron  filings  to  the  influence  of  the  atmosphere. 
The  action  of  nitric  acid  on  metallic  oxides  often  produces  it. 

3.  But  the  most  abundant  source  of  ammonia  has  been 
pointed  out,  I  believe,  by  Daubeny.  In  volcanic  districts  im- 
mense quantities  are  evolved.  This  is  formed  in  the  interior 
of  the  volcano  by  means  of  heat  and  the  decomposition  of  wa- 
ter, the  hydrogen  of  which  unites  with  the  nitrogen  of  the  air. 
This  explanation  is  rendered  evident  by  a  very  simple  exper- 

*  In  hot  countries,  the  ammonia  of  fermenting  dung  heaps,  is  part- 
ly transformed  into  nitric  acid. 

7* 


5531 


82  BIOLOGY  OF  PLANTS. 

iment ;  thus,  if  a  current  of  moist  air  is  passed  over  red  hot 
charcoal,  carbonic  acid  and  ammonia  are  readily  formed  ; 
hence  it  is  easy  to  see,  that  the  atmosphere  must  be  constant- 
ly supplied  with  variable  quantities  of  this  gas. 

What  then  is  its  influence  in  vegetation  ?  A  full  considera- 
tion of  this  agency  will  be  reserved  to  a  future  section.  It  is 
sufficient  to  remark  here,  that  it  is  supposed, 

1.  To  yield  nitrogen  to  gluten  and  to  vegetable  albumen.  It 
is  supposed  to  enter  the  vegetable  organs  either  in  a  pure 
state,  or  in  the  form  of  some  of  its  salts,  and,  by  various  trans- 
formations, to  yield  its  nitrogen  and  perhaps  its  hydrogen,  to 
the  formation  of  vegetable  substances. 

2.  To  stimulate  the  organs  of  plants  and  enable  them  to 
obtain  a  larger  quantity  of  the  substances  of  which  they  are 
composed.  But  as  plants  have  no  nerves,  such  stimulating 
effects  have  been  doubted  by  many.  The  fact,  however,  that 
light,  heat  and  electricity,  produce  effects  upon  the  functions 
of  vegetables,  analogous  to  stimulants,  shows  that  there  is  no 
good  reason  for  doubting,  that  ammonia  and  other  substances, 
may  exert  a  similar  influence.  Liebig  thinks  that  no  such  ef- 
fect is  produced,  and  accounts  for  the  powerful  influence  of 
ammonia,  on  the  principle  of  its  yielding  nitrogen,  an  essential 
constituent  of  vegetable  organs.  But  Berzelius  is  of  opinion, 
that  such  stimulating  effects  are  produced,  and  that  ammonia 
.may  act  in  this  way. 

3.  But  the  most  important  action  of  ammonia  is  its  influ- 
ence upon  the  vegetable  matter  of  the  soil,  and  upon  the  sili- 
cates. It  causes  by  its  presence  or  catalytic  power  the  decay 
of  woody  fibre,  and  renders  insoluble  geine,  soluble,  and  ca- 
pable of  entering  the  roots  of  plants.  It  also  acts  upon  the 
silicates  and  aids  to  form  nitrates,  especially  nitre,  (nitrate 
of  potassa,)  a  salt  which,  as  we  shall  show  further  along,  ex- 
erts a  powerful  influence  in  vegetation. 

IV.  Nitric  Acid  (aquafortis)  is  formed  in  the  atmosphere, 
by  the  discharge  of  electricity  in  thunder  storms.    The  quaii- 


ACIDS  OF  THE  ATMOSPHERE.  OO 

tity  has  not  been  determined,  but  we  know  from  experiment 
that  it  must  be  considerable.  A  succession  of  electric  shocks, 
through  common  air  or  ammonia,  is  attended  with  the  forma- 
tion of  nitric  acid ;  Liebig  found  this  aci*d  in  the  rain,  which 
fell  during  seventeen  thunder  storms,  generally  combined  with 
lime  and  ammonia. 

Nitric  acid,  as  we  have  seen,  p.  48,  is  composed  of  fourteen 
parts  of  nitrogen,  and  forty  parts  of  oxygen.  It  is,  therefore, 
capable  of  yielding  to  plants  one  or  both  of  these  organic  con- 
stituents. Whether  it  can  be  absorbed  by  the  leaves,  and  de- 
composed like  ammonia  and  carbonic  acid,  is  not  yet  fully  set- 
tled ;  the  fact  that  it  readily  dissolves  in  water,  renders  it  proba- 
ble, that  its  influence  is  confined,  mostly,  to  the  liquid  state ; 
and  that,  although  there  must  be  a  small  quantity  thrown  up- 
on the  leaves  of  plants  in  dew  and  rain,  and  consequently  ab- 
sorbed, yet  it  mostly  enters  the  roots  of  plants,  in  the  form  of 
some  of  its  salts,  and  is  decomposed  either  in  the  stem,  or  in 
the  leaves  by  the  agency  of  light.     (See  chapter  3.) 

V.  Light  carbureted  Hydrogen  is  found  also  in  the  atmos- 
phere in  very  small  quantities.  It  is  given  off  in  the  fermen- 
tation of  compost  heaps,  and  of  other  vegetable  matter.  It  is 
found  in  marshes,  and  rises  up  from  the  bottom  of  ponds  ;  coal 
mines  also  furnish  it.  It  is  a  colorless,  tasteless  and  inodorous 
gas,  highly  inflammable  and  explosive  when  mixed  with  air  or 
oxygen  gas,  and  is  fatal  to  life.  This  gas  is  sparingly  soluble 
in  water,  and  must  enter  the  organs  of  plants.  It  is  composed 
of  one  equivalent  of  carbon  and  two  of  hydrogen,  and  may  be 
represented  by  CH^.  Its  agency  in  vegetation  is  not  well 
knowTi.     It  may  yield  carbon  or  hydrogen  or  both  to  plants. 

VI.  Injiuenceof  the  Carbonic  Acid  of  the  Atmosphere.  Car-, 
bonic  acid  is  a  constant  ingredient  of  the  atmosphere,  but  in 
very  variable  proportions ;  generally,  less  than  one  tenth  per 
cent,  or  one  thousandth  part  by  weight,  and,  as  the  acid  is 
more  than  twice  as  heavy  as  air,  a  very  much  less  quantity  by 
volume.     According  to  Saussure  only  0,000415  of  the  vol- 


84  BIOLOGY  OF  PLANTS. 

lime  of  the  atmosphere  is  carbonic  acid.  The  quantity  varies 
according  to  the  season,  but  the  yearly  average  remains  the 
same. 

The  existence  oY  this  acid  in  the  atmosphere  is  easily  ac- 
counted for,  by  the  changes  which  are  taking  place  on  the 
surface  of  the  earth. 

1.  Large  quantities  of  carbonic  acid  are  locked  up  in  the 
rocks,  especially  in  combination  with  lime,  forming  carbonate 
of  lime,  from  which  it  is  constantly  liberated  by  chemical 
changes.  By  this  means,  also,  many  springs  constantly  emit 
it,  and  often  large  tracts  of  land  throw  it  off  from  all  parts  of 
their  surface. 

2.  In  the  process  of  combustion  this  acid  is  always  formed, 
and  the  quantity  which  is  thus  emitted  into  the  atmosphere, 
from  all  the  fires  in  the  world,  is  very  great. 

3.  The  respiration  of  animals  produces  it  in  such  quan- 
tities, that  the  respiration  of  men  alone  would  convert  all  the 
oxygen  of  the  atmosphere  into  carbonic  acid,  in  303,000  years. 
But  the  quantity  formed  by  other  animals  is  probably  greater 
than  that  formed  by  the  human  species. 

4.  The  decay  of  vegetables  is  attended  by  the  absorption 
of  oxygen,  decomposition  of  water,  and  emission  of  carbonic 
acid.     This  must  add  greatly  to  the  whole  amount. 

The  quantity  of  carbonic  acid  thrown  into  the  atmosphere 
cannot  be  determined  with  perfect  accuracy,  although  we 
know  how  much  there  is  in  the  air  at  any  one  time.  Bischof 
has  estimated  the  quantity,  evolved  from  springs  and  fissures 
in  the  ancient  volcanic  district  of  Eifel,  to  be  100,000  tons  or 
about  27,000  tons  of  carbon  annually.  Were  the  same  quantity 
to  be  sent  up  from  500  such  spots,  (fourteen  millions  of 
tons,)  it  would  only  be  equal  to  that  contained  in  the  coal, 
which  is  yearly  consumed  in  Great  Britain.  As  all  these 
causes  are  constantly  operating  we  should  suppose  that  the  at- 
mosphere would  become  deteriorated  in  a  short  time,  and  that 
the  relative  proportions  of  oxygen  and  carbonic  acid  would  be 


CARBONIC  ACID  OF  THE  ATMOSPHERE.  85 

changed  ;  the  latter  increasing  at  the  expense  of  the  former. 
But  when  we  examine  the  atmosphere,  we  find  that  there  is  a 
fixed  relation  between  these  two  substances;  one  hundred 
parts  of  air  contain  twenty  parts  of  oxygen  by  volume  in  one 
hundred,  and  from  five  to  six  y^^^  part  of  carbonic  acid  by  vol- 
ume or  about  yw<j^  P^^'t  by  weight.  So  that  the  air,  at  the 
present  day,  is  just  as  pure,  as  that  which  existed  4000  years 
ago,  and,  although  billions  of  cubic  feet  of  carbonic  acid  are 
thrown  off  into  the  air,  and  an  equal  volume  of  oxygen  con- 
sumed, (one  man  consuming  45,000  cubic  inches  per  day,) 
still,  this  relation  is  not  disturbed. 

How  is  this  acid  disposed  of?  and  from  what  source  is  the 
oxygen  derived  to  fill  its  place  ?  for  a  cubic  foot  of  oxygen 
gas,  by  uniting  with  carbon,  so  as  to  form  carbonic  acid,  does 
not  change  its  volume.  The  billions  of  cubic  feet  of  oxygen 
extracted  from  the  atmosphere,  are  replaced  by  the  same  num- 
ber of  billions  of  cubic  feet  of  carbonic  acid  which  immediate- 
ly supply  its  place.  There  must  be  some  cause,  or  causes, 
which  exists,  capable,  both  of  removing  the  carbonic  acid, 
and  of  replacing  an  equal  volume  of  oxygen,  which  is  removed 
from  the  air,  by  the  processes  above  described.  This  cause 
is  to  be  found,  principally,  in  the  process  of  vegetation. 

1.  The  carbonic  acid  of  the  atmosphere  is  absorbed  and  de- 
composed by  vegetables ;  its  carbon  assimilated,  and  its  oxy- 
gen given  back  to  the  atmosphere. 

All  the  green  parts  of  plants  are  capable  of  absorbing  this 
gas,  but  the  property  is  mostly  confined  to  the  leaves,  which 
possess  it,  quite  independent  of  the  plant  itself,  as  they  per- 
form the  function  of  absorbing  carbonic  acid,  and  emitting 
oxygen  when  separated  from  the  stalk.  The  upper  surfaces 
of  leaves  appear  to  have  peculiar  organs  of  absorption,  as  they 
will  not  perform  this  function  when  bruised.  The  presence 
of  light  is  necessary,  in  order  that  the  leaves  may  decompose 
carbonic  acid.  This  fact  was  first  proved  by  Ingenhouse, 
who  also  found,  that  plants  emit  no  oxygen  gas,  when  made 


86  BIOLOGY  OF  PLANTS. 

to  vegetate  in  the  dark.  In  the  light  the  leaves  decompose 
the  acid,  assimilate  the  carbon  and  a  part  of  the  oxygen,  while 
the  remainder  is  yielded  to  the  atmosphere.  In  the  dark, 
the  reverse  takes  place  ;  the  leaves  absorb  oxygen,  and  the 
carbonic  acid  is  not  decomposed,  but  is  thrown  out  into  the 
air  ;  hence,  as  little  carbon  is  assimilated,  plants  which  grow 
in  the  shade,  or  in  a  cellar,  are  soft,  spongy,  pale  and  sickly.* 
The  quantity  of  acid,  absorbed  during  the  day,  and  decom- 
posed, is  greater  than  that  given  out  during  the  night,  and 
the  quantity  of  oxygen  emitted  by  day  exceeds  that  absorbed 
at  night ;  hence,  the  atmosphere  furnishes  carbonic  acid  to 
plants,  and  they  in  turn  furnish  oxygen  to  the  air.  Carbonic 
acid  thus  performs  a  similar  office  to  vegetables  which  oxy- 
gen does  to  animals,  the  former  purifies  the  juices  of  the  veg- 
etable, the  latter  the  blood  of  the  animal ;  hence,  the  animal 
and  vegetable  kingdoms  contribute  to  each  other's  support. 
Animals  absorb  oxygen,  and  convert  it  into  carbonic  acid  ; 
vegetables  absorb  the  acid  thus  formed,  and  give  back  to  the 
air  an  equal  volume  of  oxygen,  necessary  to  support  animals. 
Thus  the  equilibrium  of  the  atmosphere  is  maintained,  and 
both  kingdoms  flourish  together. 

Although  an  equal  volume  of  gas,  is  given  back  to  the  at- 
mosphere, when  carbonic  acid  is  decomposed  by  the  leaves 
under  the  influence  of  solar  light,  it  is  not  all  oxygen,  but  a 
part  of  it  is  nitrogen.  Saussure  found  that  of  2.1 .75  cubic  inch- 
es of  carbonic  acid  absorbed,  only  14.72  inches  of  oxygen  was 
given  back,  together  with  seven  inches  of  nitrogen ;  part  of 
the  oxygen  is  thus  assimilated  to  the  plant. 

2.  The  quantity  of  carbonic  acid,  thus  absorbed,  has  been 
determined  with  some  degree  of  certainty.  In  Saussiire's  ex- 
periments, plants  absorb  daily,  more  than  their  bulk,  and,  as 
this  acid  is  composed  of  6.12  parts  by  weight  of  carbon,  and 
16  of  oxygen  in  22.12,  it  is  possible  to  calculate  the  probable 
amount  of  carbon,  which  is  derived  from  this  source.     The 

*  See  Chaptal,  p.  81. 


CARBONIC  ACID  OF  THE  ATMOSPHERE.  87 

quantity  is  so  great  that  a  distinguished  chemist  (Liebig)  has 
advocated  the  opinion,  that  plants  derive  their  carbon  wholly 
from  the  carbonic  acid  of  the  atmosphere.* 

The  quantity  of  acid  thus  absorbed  and  decomposed  varies 
greatly  in  different  plants,  even  when  placed  under  the  same 
circumstances.  Saussure  has  proved  that  the  portion  depends 
upon  the  surface  ;  hence,  those  plants,  which  have  thin  leaves, 
absorb  more  than  the  Jleshif-leaved  plants.  The  same  is  true, 
as  we  have  seen,  with  regard  to  their  power  of  absorbing  oxy- 
gen gas. 

Plants  require  different  quantities  of  carbonic  acid  at  dif- 
ferent periods  of  their  growth.  The  young  plant  requires  but 
little,  because  its  leaves  are  not  sufficiently  vigorous  to  absorb, 
and  decompose  it.  The  quantity  required  increases  with  the 
size  of  the  leaves ;  hence,  the  greatest  quantity  is  required 
when  the  leaves  have  obtained  a  mature  growth,  which  peri- 
od is  near  the  middle  of  summer  in  most  plants,  and  it  is  at 
this  period  that  the  greatest  quantity  is  furnished  by  the  fer- 
mentation of  manures,  and  vegetable  substances  in  the  soil. 

Carbonic  acid  has  been  considered  prejudicial  to  the  ri" 
pening  of  grain,  because  its  presence,  in  large  quantities, 
stimulates  the  leaves,  and  increases  their  bulk  at  the  expense 
of  the  grain. 

As  plants  during  the  summer  season  absorb  the  carbonic 
acid  of  the  atmosphere,  it  would  seem  that  during  the  winter 
season  a  much  larger  quantity  would  be  found  in  the  air,  than 
in  the  summer ;  particularly  as  larger  quantities  are  produ- 
ced by  combustion,  and  smaller  quantities  brought  to  the  earth 
by  rain.  This  would  be  the  case  were  it  not  for  the  fact  that 
in  the  tropics  there  is  always  a  vigorous  vegetation  ;  the  air 
is  constantly  circulating  from  the  tropics  towards  the  poles, 
and  the  reverse.  By  this  constant  motion  the  equilibrium 
is  maintained,  and  there  actually  is  a  larger  quantity  of  acid 
in  the  air  in  the  summer  than  in  the  winter,  because  the 

*  See  third  chapter. 


88  BIOLOGY  OF  PLANTS. 

causes  of  its  production  are  more  abundant,  and  some  of 
them  more  active. 

There  are  other  causes  which  tend  to  abstract  the  carbon- 
ic acid  from  the  atmosphere. 

1.  As  we  approach  the  centre  of  lakes  or  sail  out  upon  the 
sea,  ihe  carbonic  acid  of  the  air  gradually  diminishes.  This 
we  know  is  due  to  the  fact  that  the  water  absorbs  it  in  large 
quantities,  but  as  it  is  capable  of  absorbing,  under  the  ordina- 
ry pressure,  only  a  quantity  equal  to  its  own  bulk,  we  should 
suppose  that  it  would  soon  become  saturated  ;  this,  however, 
is  not  the  case,  and  the  water  does  not,  so  far  as  is  known, 
return  it  again  to  the  atmosphere,  but  disposes  of  it  in  some 
other  way. 

2.  The  water  of  rivers  is  constantly  carrying  down  sub- 
stances which  have  derived  carbonic  acid  from  the  atmos- 
phere, and  it  thus  becomes  fixed  in  the  bottoms  of  lakes  and 
seas. 

3.  In  temperate  climates,  vegetable  matter  accumulates  in 
the  form  of  peat  which  permanently  fixes  large  quantities  of 
this  acid. 

The  presence  of  carbonic  acid  is  absolutely  essential  to  veg- 
etation. This  fact  has  been  shown  by  Saussure,  who  found 
that  when  lime  was  put  into  a  glass  vessel  containing  plants, 
so  that  the  carbonic  acid,  both  of  the  air  and  of  the  soil,  was 
absorbed,  they  no  longer  continued  to  grow,  and  the  leaves 
in  a  few  days  fell  off.  On  examining  the  air,  it  was  found 
to  be  deprived  of  carbonic  acid  ;  if,  however,  the  plant  is 
placed  in  the  shade,  the  presence  of  lime  to  absorb  the  car- 
bonic acid  promotes  vegetation ;  that  is,  plants  grow  better 
without  the  acid  in  the  shade  than  with  it.  This  process, 
however,  cannot  be  continued  long,  as  the  presence  of  light 
and  acid  are  required  to  continue  vigorous  growth. 

By  adding  a  small  quantity  of  carbonic  acid  to  that  which 
already  exists  in  the  atmosphere,  vegetation  is  promoted. 
When  the   atmosphere  contains  ^L-  part  of  carbonic  acid. 


PRESSURE  OF  THE  ATMOSPHERE.  89 

plants  vegetate  much  better  in  the  sun  than  when  placed  in 
common  air,  but  a  larger  quantity  proves  injurious,  and  when 
an  atmosphere  contains  three  fourths  of  its  volume  of  that  gas, 
plants  will  not  vegetate  at  all,  any  more  than  they  will  in  the 
pure  acid.  Any  addition  of  the  gas  in  the  shade,  retards  ra- 
ther than  promotes  vegetation.  Sennebier  has  shown,  that 
the  green  color  of  plants  depends  upon  the  absorption  of  car- 
bonic acid ;  for  this  purpose  light  and  oxygen  gas  must  also 
be  present. 

It  is  a  fact  worthy  of  notice,  in  this  connection,  that  carbon^ 
ic  acid,  which  is  so  essential  to  vegetation,  and  so  grateful  to 
be  used  in  solution,  as  a  drink,  acts,  nevertheless,,  as  a  slow 
poison  when  taken,  much  diluted  with  air,  into  the  lungs  of  an- 
imals, and  produces  almost  instant  death,  when  introduced 
in  a  pure  state. 

As  it  is  produced  by  ordinary  combustion,  every  year  adds 
many  melancholy  examples  of  its  fatal  power,  in  the  case  of 
those  who  are  so  imprudent,  as  to  use  live  coals  to  warm 
sleeping  apartments,  which  are  not  properly  ventilated,  or  who 
use  furnaces  for  ironing,  and  for  culinary  purposes.   The  acid, 
being  heavier  than  the  air,  fills  the  apartment  like  water,  and 
as  soon  as  the  individual  dips  his  head  into  it,  he  is  suffocated 
almost  as  soon  as  if  plunged  into  water. 
VII.  3Iechanical  agency  of  the  atmosphere. 
1.   The  pressure  of  the  air  is  of  the  highest  importance  to 
the  vegetable  kingdom.     As  the  pressure  is  about  lolbs.  upon 
every  square  inch  of  surface,  its  force  upon  the  leaves  and 
other  parts  of  plants  must  be  very  great.     It  brings  the  oxy- 
gen, carbonic  acid  and  ammonia  into  direct  contact  with  the 
various  organs  of  absorption.     It  also  furnishes  support  to  the 
external  surface  of  plants,  and  enables  them  to  withstand  the 
pressure  of  the  fluids  within  ;  for  were  the  atmosphere  very 
rare,  or  wholly  removed,  the  processes  within  the  plant  would 
injure  or  burst  the  vessels,  and  decay  and  death  would  ensue. 
As  we  ascend  above  the  level  of  the  ocean  this  pressure 
8 


90  BIOLOGY  OF  PLANTS. 

diminishes ;  hence,  plants  which  grow  on  high  mountains, 
receive  less  of  the  support  above  mentioned.  It  may  be  due 
to  this  circumstance,  that  plants  w\\\\  fleshy  leaves  flourish  best 
in  such  regions. 

2.  The  atmosphere  not  only  furnishes  food  and  support  to 
vegetables,  but  it  is  the  medium  of  communicating  nourish- 
ment, and  for  the  action  of  other  agents.  It  is  by  the  agen- 
cy of  the  atmosphere  that  water  is  borne  up  from  the  ocean, 
and  distributed  to  every  part  of  the  land,  in  the  form  of  rain 
and  dew, — that  carbonic  acid,  ammonia,  odoriferous  and  sa- 
line particles  are  conveyed  to  the  organs  of  plants.  Its  per- 
fect elasticity,  yielding  to  the  slightest  pressure,  and  its  con- 
stant motion,  give  to  plants  their  proper  exercise,  without  the 
slightest  injury.  It  is  the  medium  for  the  agency  of  light, 
heat  and  electrical  changes,  which  are  intimately  connected 
with  the  vital  functions  of  plants.  Bearing,  as  it  does,  the 
clouds  on  its  bosom,  it  furnishes  an  opportunity  for  some  of 
the  most  sublime  and  beautiful  phenomena  of  the  natural 
world. 

The  influence  of  the  moisture  of  the  atmosphere  will  be 
considered  in  the  next  section. 

Such  are  the  elements  of  our  atmosphere,  and  their  import- 
ant influence  upon  the  vegetable  kingdom.  Its  constitution 
and  properties  render  it  beautifully  and  wisely  fitted  for  its 
indispensible  agency.  The  manner  in  which  its  elements  are 
combined,  exhibits,  in  a  striking  light,  the  wisdom  and  be- 
nevolence of  the  Creator.  The  oxygen,  nitrogen,  and  other 
gaseous  bodies,  of  which  the  atmosphere  is  composed,  seem 
not  to  be  governed,  as  they  are  in  other  combinations,  strict- 
ly by  the  laws  of  chemical  affinity,  or  of  mechanical  mixture. 
Its  constitution  appears  to  be  an  exception  to  general  laws, 
for  the  special  benefit  of  the  animal  and  vegetable  kingdoms. 
Its  elements  obey  nearly  the  laws  of  combination,  which  they 
observe  when  they  combine  in  other  proportions ;  and  yet, 
they  are  so  loosely  united  to  each  other,  that  each  seems  to 


BENEVOLENCE  OF  GOD.  91 

be  diffused  through  the  other,  forming  independent  atmos- 
pheres hke  a  wheel  within  a  wheel.  So  that  any  element, 
which  the  wants  of  the  animal  or  the  plant  may  require,  is 
easily  and  readily  abstracted. 

But  what  should  most  excite  our  astonishment,  as  well  as 
our  gratitude,  is  the  fact,  that  out  of  the  six  distinct  and  dif- 
ferent compounds,  which  may  be  formed  from  the  union  of 
oxygen  and  nitrogen,  and  these  two  bodies  compose  almost 
the  entire  volume  of  the  atmosphere,  only  one  is  fitted  to  the 
wants  of  the  animal  and  vegetable  economy.  Five  parts  of 
nitrogen  and  one  of  oxygen,  by  weight,  form  the  atmosphere ; 
fourteen  of  nitrogen  and  eight  of  oxygen  form  the  exhilarat- 
ing gas,  a  most  powerful  stimulant ;  fourteen  of  nitrogen  and 
sixteen  of  oxygen  form  a  substance,  the  breathing  of  which 
causes  almost  instant  death  :  fourteen  of  nitrogen  and  twen- 
ty-four of  oxygen  form  a  poisonous  liquid ;  thirty-two  of  oxy- 
gen and  fourteen  of  nitrogen  form  one  of  the  most  poisonous 
gases  known ;  forty  parts  of  oxygen  and  fourteen  of  nitrogen 
form  the  well  known  substance,  nitric  acid  (aquafortis). 
One  of  these  compounds,  and  that  too  the  most  injurious, 
nitrous  acid,  is  formed  in  the  atmosphere  during  thunder 
storms.  If  the  atmosphere  were  suddenly  changed  into  this 
acid,  the  whole  face  of  nature  would  be  almost  instantly 
clothed  with  the  pall  of  death.  Why  do  not  the  elements  of 
the  atmosphere  change  their  proportions,  and  produce  this  re- 
sult? Why,  but  for  the  constant,  unceasing,  all-pervading 
agency  of  a  wise  and  benevolent  Intelligence. 

The  composition  and  properties  of  our  atmosphere  adapt 
it  to  a  great  variety  of  other  purposes,  aside  from  its  influence 
upon  the  vegetable  kingdom.  Its  density  and  elasticity  are 
exactly  fitted  to  the  delicate  structure  of  our  lungs.  Increase 
its  density  to  that  of  water,  and  we  should  need  lungs  of  ada- 
mant ;  diminish  it  to  that  of  hydrogen,  and  our  life's  blood 
would  rush  out  at  every  pore.  This  beautiful  adaptation  of 
our  atmosphere  to  the  animal  and  vegetable  kingdoms,  not 


92 


BIOLOGY  OF  PLANTS. 


only  exhibits  the  skill  and  benevolence  of  Him  who  estab- 
lished and  upholds  the  laws  by  which  it  is  governed ;  but 
challenges  the  constant  gratitude  of  those,  who  can  offer  no 
other  return  for  having  been  placed  under  a  constitution  so 
wisely  ordered  for  their  good. 

Sect.  2.  Agency  of  Water  upon  tlie  Vital  Functions  of  Plants. 

Water  is  a  compound  body,  and  may  easily  be  decomposed 
by  galvanism,  or  by  adding  to  it  sulphuric  acid  and  iron  turn- 
ings. By  these  processes  it  is  shown  to  be  composed  of  eight 
parts,  by  weight,  of  oxygen  to  one  of  hydrogen,  or  of  one 
volume  of  the  former  to  two  of  the  latter ;  its  constituents, 
therefore,  hydrogen  and  oxygen,  enter  into  the  composition 
of  vegetables  in  large  quantities. 

Water  is  found  under  three  different  forms,  solid,  liquid 
and  gaseous. 

I.  In  the  solid  form,  as  in  ice  and  snow,  water  exerts  con- 
siderable agency  upon  the  living  functions  of  plants.  This 
it  does,  either  by  its  influence  upon  the  soil,  or  upon  the  seeds 
and  roots  of  plants. 

1.  When  water  freezes  in  the  soil,  it  tends  to  expand  it, 
and  to  break  down  its  coarser  parts ;  when  the  surface  thaws 
in  the  spring,  the  top  melts  first,  and  there  is  produced  small 
apj^ertures  through  which  the  mellowing  and  ameliorating  in- 
fluence of  the  atmosphere  is  exerted.  Heavy  clay  lands  are 
thus  often  highly  benefited. 

*2.  Snow  is  supposed  to  be  beneficial  to  winter  wheat  and 
other  crops.  This  it  does  by  protecting  the  crop  and  the 
soil  from  the  influence  of  severe  cold.  It  forms  a  light,  po- 
rous covering,  which  is  an  excellent  non-conductor  of  heat, 
and  hence  prevents  the  warmth  of  the  earth  from  escapftig.  On 
the  same  principle,  by  covering  the  young  shoots  of  plants,  it 
defends  them  from  the  influence  of  sudden  varieties  of  tem- 
perature.    When  the  rays  of  the  sun  fall  suddenly  upon  a 


AGENCY  OF  WATER.  93 

frozen  shoot,  it  droops  and  turns  black  ;  but  if  it  be  thawed 
gradually,  it  will  not  be  injured.  This  is  supposed  to  be  due 
to  the  fact,  that  as  the  fluids  in  the  vegetable  organs  freeze, 
they  expand,  but  the  air  contained  in  adjacent  vessels  suf- 
fers a  corresponding  contraction,  so  that  the  organs  are  rare- 
ly burst  by  frost.  When  sudden  heat  is  applied  to  the  plant, 
in  this  state,  the  air  expands  more  rapidly  than  the  ice  con- 
tracts, arid  the  vessels  are  burst ;  but  when  the  plant  is  thawed 
more  slowly  no  such  effect  is  produced.  Hence  the  reason 
for  putting  frozen  vegetables  into  water,  where  they  will  thaw 
gradually,  in  order  to  preserve  them.  Potatoes  may  thus  be 
preserved  frozen  during  the  winter,  and  by  thawing  them 
slowly  and  drying  rapidly  they  are  not  injured.  Liebig  has 
shown  that  snow  contains  ammonia,  and  this  fact  will  serve 
to  explain  its  influence  upon  winter  wheat.  It  also  absorbs 
oxygen  and  nitrogen,  in  proportions  quite  different  from  those 
in  the  atmosphere.  The  oxygen  is  only  about  seventeen  in- 
stead of  twenty-one  per  cent.  Dana  has  shown  that  an  acre 
receives  annually  fifty  pounds  of  geine  and  salts  in  the  snow. 

II.  The  agency  of  water,  in  the  liquid  form,  may  be  con- 
veniently studied  under  the  following  heads.  1.  Its  solvent 
properties ;  2.  Its  chemical  agency ;  3.  Its  mechanical  agen- 
cy ;  and,  4.  As  affording  food. 

1.  Solvent  properties  of  water.  Water  has  the  power  of 
dissolving,  and  holding  in  solution  a  great  variety  of  sub- 
stances, animal,  vegetable  and  mineral.  It  is  the  great  sol- 
vent in  all  the  operations  of  nature. 

(1)  When  water  passes  through  the  soil,  it  dissolves  out 
its  soluble  salts,  such  as  common  salt,  potash,  lime,  nitre,  etc., 
and  conveys  these  substances  to  the  roots,  and  thence  into 
the  organs  of  vegetables. 

(2)  Water  dissolves  out  the  soluble  parts  of  vegetable  mould 
and  of  compost  manures,  as  fast  as  the  chemical  changes  in 
the  soil  render  them  soluble,  and  fitted  for  the  nourishment  of 

8* 


94 


BIOLOGY  OF  PLANTS. 


plants.     It  thus  presents  these  matters  in  a  form  capable  of 
entering  the  organs  of  absorption. 

(3)  In  a  similar  manner,  also,  by  passing  over  animal  mat- 
ters, such  as  horns,  bones,  wool  and  animal  manures,  water 
dissolves  those  parts  which  are  fitted  for  nutriment,  as  fast  as 
formed,  and,  in  a  similar  way,  facilitates  their  introduction 
into  the  vegetable  organs. 

(4)  Water  also  absorbs  various  gaseous  compounds,  such 
as  common  air,  carbonic  acid  and  ammonia ;  prevents  them 
from  escaping  beyond  the  reach  of  the  plant,  and  conveys 
them  into  the  appropriate  vessels.  The  quantity  of  carbonic 
acid  which  water  is  capable  of  absorbing  is  equal,  at  the  com- 
mon temperature  and  pressure,  to  its  own  volume. 

The  quantity  of  ammonia  is  much  larger,  amounting,  ac- 
cording to  Thompson,  in  some  cases,  to  seven  hundred  and 
eighty  times  its  bulk.  These  substances  are  brought  to  the 
earth  by  every  shower  of  rain,  or  are  absorbed  as  soon  as 
formed,  in  the  soil.  The  agency  of  water  in  this  respect  is 
of  the  highest  importance  in  the  nourishment  of  plants,  because 
most  of  the  manures  which  are  added  to  soils,  throw  off  in  the 
process  of  decay,  large  quantities  of  these  gases,  which  would 
be  mostly  lost  for  the  purposes  of  nutrition,  were  they  not  in- 
stantly absorbed  by  the  water,  and  retained  for  the  use  of  the 
plant.  The  air  which  the  water  holds  in  solution,  is  much  less, 
and,  as  we  have  seen,  is  needed  in  the  process  of  germination, 
in  a  free  state.  Generally,  aJl  bodies  which  in  any  way  con- 
stitute the  food  of  plants,  must  first  be  dissolved  in  water  be- 
fore they  can  be  introduced  into  the  roots,  and  become  a  part 
of  the  living  system. 

2.  Chemical  agency  of  ivattr.  In  the  process  of  decay, 
putrefaction,  fermentation,  etc.  by  which  food  is  prepared  for 
the  nourishment  of  plants,  water  is  always  decomposed,  its 
hydrogen  combining  with  the  oxygen  of  the  air,  and  its  oxy- 
gen with  the  carbon  of  the  decaying  vegetable,  forming  car- 
bonic acid,  and  other  compounds,  which  are  found  in  the  hu- 


AGENCY  OP  WATER.  96 

mus,  oi"  vegetable  mould  of  soils.  It  is  also  decomposed  by 
the  mineral  constituents  of  the  soil,  and  by  the  putrefaction 
of  animal  matters  ;  hence  we  may  explain  the  fact,  that  soils, 
by  being  left  to  rest  for  a  few  years,  have  their  fertility  re- 
stored. This  is  principally  due  to  the  oxygen  of  the  water 
and  of  the  air.  This  agency  of  water  in  the  decay  of  vegeta- 
ble matter  in  the  soil,  is  somewhat  remarkable,  as  its  hydro- 
gen combines  directly  with  the  oxygen  of  the  air,  which,  with 
the  hydrogen  of  the  vegetable,  return  more  water  to  the  soil 
than  is  abstracted.  In  the  process  of  germination,  water,  as 
we  have  seen,  is  decomposed,  and  yields  its  oxygen  to  the  car- 
bon of  the  germ. 

3.  Mechanical  agency  of  icater.  (1)  The  first  effect  of 
water,  in  this  respect,  is  to  penetrate  the  outer  covering  of  the 
seed,  and  to  divide  the  soil  so  as  to  permit  the  roots  of  plants 
to  extend  themselves  freely  in  every  direction. 

(2)  The  second  is  to  convey  to  the  roots  the  matter  which 
it  holds  in  solution.  In  this  latter  respect  it  is  equally  useful 
with  the  atmosphere  itself  In  passing  over  rocks  it  wears  off 
their  particles,  which,  with  portions  of  the  soil,  and  other  mat- 
ters, remain  mechanically  suspended  in  it.  This  matter  is 
spread  over  the  valleys  by  the  overflowing  of  streams.  Wa- 
ter is  thus  constantly  at  work  in  wearing  down  the  mountains 
and  bringing  down  their  valuable  contents  upon  the  plains,  or 
forming  new  land  by  the  sides,  or  at  the  mouths  of  rivers.  In 
this  way,  it  becomes  the  greatest  fertilizer  known. 

(3)  When  however  it  flows  through  soils  charged  with  some 
metallic  salt,  like  the  sulphate  of  iron  {copperas),  it  proves  in- 
jurious to  vegetation,  and  lime,  or  some  alkali,  must  be  added 
to  decompose  the  salt,  and  destroy  its  corrosive  or  poisonous 
properties. 

4.  Agency  of  water  as  nutriment.  In  addition  to  the  agen- 
cy of  water  above  described,  it  is  used  by  plants  as  food.  We 
know  that  it  constitutes  a  large  portion  of  the  juices  of  plants, 
and,  although  a  large  portion  of  that  which  enters  the  roots  is 


96  BIOLOGY  OF  PLANTS. 

transpired  by  the  leaves,  it  is  not  all  thus  disposed  of;  the  hy- 
drogen, which  is  found  in  such  abundance  in  vegetables,  can 
be  obtained  from  no  other  source.  The  vital  power  is  able 
to  decompose  the  water,  and  assimilate  its  hydrogen,  while 
its  oxygen  is  either  combined  with  some  other  body,  and  re- 
jected as  excretory  matter ;  or  assimilated  also  to  the  vegeta- 
ble structure.  Many  vegetable  bodies,  as  woody  fibre,  con- 
tain carbon  and  the  elements  of  water,  hydrogen  and  oxygen, 
in  the  same  relative  proportions  as  in  water,  and  hence  water 
may  be  directly  assimilated. 

III.  Water  in  the  state  of  vapor  ministers  to  the  life  and 
growth  of  plants,  in  a  manner  but  little  less  effectual  than  in 
the  liquid  form.  It  boils  and  is  converted  into  steam  at  212° 
F.,  but  the  quantity  of  vapor  thus  produced  is  very  small,  com- 
pared with  that  which  rises  at  all  temperatures*  by  a  process 
called  evaporation,  a  process  which  is  promoted  by  a  high 
temperature,  extent  of  surface,  and  the  dryness  and  motion  of 
the  atmosphere. 

1.  By  the  constant  evaporation  of  water  from  the  surface 
of  the  ocean  and  the  land,  from  the  leaves  of  vegetables  and 
the  bodies  of  animals,  large  quantities  of  vapor  are  thrown  off 
into  the  atmosphere.  This  quantity  is  found  to  vary  with  the 
temperature.  At  50°  F.  the  atmosphere  contains  about  j\j 
or  yL  part  of  its  weight.  At  100°  F.  about  ■j\  or  j\y  part  of 
its  weight.  When  the  temperature  is  diminished,  it  is  con- 
densed and  appears  in  the  form  of  vapor,  or  is  deposited  in 
the  state  of  dew  ;  hence  the  diminution  of  temperature,  dur- 
ing the  night,  precipitates  a  quantity  of  moisture  upon  veg- 
etables, and  restores  their  freshness  and  vigor. 

2.  The  leaves  and  7'oots  have  the  power  of  absorbing  the 
water  thus  thrown  upon  them,  and,  according  to  Liebig,  af- 
ter their  organs  of  nutrition  are  fully  matured,  derive  nearly 

*  Major  Sabine  states  that  in  the  intense  cold  of  the  polar  seas,  not 
only  living  bodies,  but  the  very  snoto  smokes,  and  fills  the  air  with 
vapor. 


AGENCY  OF  DEW.  97 

or  quite  enough  from  this  source  for  the  purposes  of  assimi- 
lation. The  dew  conveys  also  carbonic  acid  and  ammonia, 
which  we  have  seen  are  indispensable  to  vegetation. 

3.  But  aside  from  the  direct  agency  of  water  as  an  aliment, 
which  we  have  already  considered,  the  atmosphere  performs 
an  important  agency  in  yielding  it,  at  the  time  when  its  pres- 
ence is  most  needed  to  modify  the  effects  which  are  produced 
by  the  heat  of  the  sun.  This  influence  is  always  beneficial, 
but  almost  indispensable  in  dry  seasons.  The  moisture  which 
the  air  contains  is  conveyed,  during  the  night,  to  all  parts  of 
plants,  not  excepting  their  roots,  if  the  soil  is  in  a  proper  con- 
dition to  admit  a  circulation  of  air.  In  some  countries,  as 
Egypt,  there  is  no  rain  for  several  months  ;  this  defect  is,  in 
part,  made  up  by  the  heavy  dews  which  fall  during  the  night, 
and  tend  to  restore  the  languishing  energies  of  the  vegetable 
kingdom.  It  is  owing  to  the  direct  agency  of  the  dew  upon 
the  roots  of  plants,  that  the  earth  should  be  stirred  about 
them,  so  as  to  keep  it  light,  and  always  permeable  to  the  air. 

4.  The  agency  of  water  in  the  form  of  dew  presents  the 
most  striking  illustration  of  its  utility,  and  of  its  wise  and 
beautiful  adaptation  to  the  vegetable  kingdom.  All  bodies 
radiate  heat  into  space  during  the  night.  The  surface  of  the 
earth  gives  off  more  heat  than  it  receives,  and  the  dew  is  de- 
posited. But  it  should  be  remarked,  that  some  bodies  cool 
much  more  rapidly  than  others ;  hence  these  bodies  will  first 
attract  the  particles  of  falling  dew.  Thus  the  grass  plot  is 
wet,  while  the  gravel  walk  is  dry.  The  dew  thus  seems  to 
select  the  object  which  it  would  cherish,  and,  after  having 
ministered  to  the  wants  of  every  living  plant,  spends  its  su- 
perfluity only  on  the  naked  earth  or  barren  waste. 

5.  The  water  thus  distilled  into  the  air,  is  precipitated,  not 
only  in  glistening  dew  drops,  but  in  refreshing  showers  of 
rain.  This  arrangement  is  exceedingly  beautiful,  if  we  con- 
sider the  fact,  that  were  all  the  vapor  condensed  at  once,  it 
would  not  cover  the  earth  more  than  five  inches  in  depth ; 


yy  BIOLOGY  OF  PLANTS. 

but  that  the  quantity  which  mimially  falls  is,  upon  an  average, 
thirty-three  inches  in  depth.  Hence  the  water,  which  so  con- 
stantly ministers  to  vegetation,  must  be  distilled  five  or  six 
times  during  every  year, 

6.  The  process  of  evaporation  of  water  produces  cold,  hence 
we  may  explain  the  reason  that  wet  soils  and  clayey  lands  are 
called  cold  soils.  The  water  which  is  everywhere,  and  constant- 
ly passing  into  the  state  of  vapor,  absorbs  large  quantities  of 
heat,  so  as  to  produce  a  difference  of  temperature  in  the  air 
of  two  adjacent  fields.  The  only  remedy  is  thorough  drain- 
ing. 

Such  is  the  indispensable  agency  of  water  in  the  vegetable 
economy.  It  is  the  vital  fluid  of  plants.  Upon  its  proper 
regulation  depends  the  quantity,  quality  and  perfection  of 
most  of  the  products  of  the  earth,  especially  of  those  intend- 
ed for  the  use  of  man. 

Its  constitution  and  properties,  its  abundance  and  univer- 
sality, illustrate  the  beneficent  provisions  of  the  Creator  for 
the  preservation  and  sustenance  of  animal  and  vegetable  life; 
so  that  here,  as  in  all  his  other  operations,  and  throughout  all 
his  works,  has  he  shown  the  same  skill  and  goodness.  In 
the  midst  of  this  unbounded  profusion,  nothing  is  wasted, 
nothing  is  supplied  without  a  purpose.  Dead  matter  and 
material  agencies  are  all  made  subservient  to  the  demands 
oflife. 


Sect.  3.  Influence  of  the  Imponderable  Agents  upon  the  vital 
Fhinctions  of  Plants. 

These  agents  are  gravity,  cohesion,  affinity,  caloric,  light 
and  electricity.  They  are  the  great  natural  forces  or  causes 
of  change  in  the  materiiU  world.  I  shall  consider  them  here, 
only  in  their  relations  to  vegetation,  or  in  their  influence  up- 
on the  vital  power. 

I.  Gravity.     Gravity  or  the  attraction  of  gravitation  is  that 


^  INFLUENCE  OF  GRAVITY.  99 

power  which  all  bodies,  in  masses,  possess  of  attracting  each 
other.  Gravity  causes  a  stone  and  all  heavy  bodies  throuTi 
into  the  air  to  fall  to  the  earth.  The  direction  of  this  force 
is  towards  the  centre  of  the  body ;  hence,  all  bodies  falling  to 
the  earth,  if  not  arrested  at  its  surface,  would  pass  on  direct- 
ly to  its  centre.  This  force  is  the  cause  of  the  pressure  of 
the  atmosphere,  and  of  water,  as  well  as  of  their  motion.  Wa- 
ter, by  the  force  of  gravity,  falls  from  the  clouds,  penetrates 
the  earth,  and  hurries  to  the  ocean  in  streams  and  rivers. 

The  principal  effect  of  gravity  upon  the  functions  of  vege- 
tables, is  the  influence  it  exerts  upon  the  direction  of  their 
roots  and  branches.  This  influence  was  proved  by  the  ex- 
periments of  Mr.  Knight,  who  fixed  some  seeds  of  the  garden 
bean  on  the  circumference  of  two  wheels,  the  one  made  to 
revolve  rapidly  in  a  horizontal  direction,  and  the  other  in  a 
vertical  direction.  The  beans  were  supplied  with  the  requi- 
site conditions  for  germination,  and  although  the  revolutions 
on  the  vertical  wheel  were  two  hundred  and  fifty  per  minute, 
and  those  on  the  horizontal,  one  hundred  and  fifty,  the  beans 
all  grew.  The  roots  in  the  vertical  wheel  pointed  in  the  di- 
rection of  the  radii,  and  the  stalks  towards  the  centre  where 
they  soon  met.  In  the  horizontal  wheel  the  centrifugal  force 
conflicted  with  that  of  gravitation,  and  caused  the  stems  or 
stalks  to  meet,  in  the  form  of  a  cone,  over  the  centre  of  revo- 
lution, while  the  roots  took  an  opposite  direction.  There 
can  be  no  doubt,  that  gravity  exerts  considerable  influence  on 
the  direction  of  the  roots  and  stems  of  plants,  and  yet  the  rea- 
son why  the  seed  takes  root  downward,  and  bears  fruit  up- 
ward, must  be  attributed  to  the  laws  of  vitality  * 

II.  Cohesion.  Cohesive  attraction  holds  the  parts  of  bo- 
dies together.  This  is  shown  when  two  leaden  bars  are 
scraped  smooth,  and  pressed  together  ;  they  will  adhere  with 
a  force  proportioned  to  the  closeness  of  their  contact.  If  that 
is  perfect,  the  bar  will  yield  in  any  other  part  as  easily  as  at 

*  See  Davy's  Ag.  Chemistry. 


100  BIOLOGY  OF  PLANTS. 

the  point  of  junction.  Cohesion  gives  to  fluids  a  globular 
form  as  in  the  case  of  drops  of  water.  A  modification  of  this 
power,  called  capillary  attraction,  has  considerable  influence 
in  the  ascent  of  the  sap  through  the  common  vessels,  and  in 
the  absorption  of  moisture  by  the  leaves  and  roots  of  plants. 
The  mode,  in  which  this  is  done,  may  be  shown  by  placing 
straws  in  a  basin  of  water  ;  the  water  in  the  straws  will  rise 
much  higher  than  that  in  the  basin.  The  principle  is  exem- 
plified in  the  wick  of  a  lamp,  the  oil  being  drawn  up  by  this 
power  ;  also  in  the  sponge,  in  sugar,  and  almost  any  body  con- 
taining small  tubes  or  pores.  The  force  of  cohesion,  however, 
does  not  fully  account  for  the  ascent  of  the  sap,  although  it 
may  aid  other  forces  in  promoting  its  circulation. 

III.  Chemical  Affinity.  This  power  differs  from  gravita- 
tion and  cohesion  in  the  circumstance,  that  its  force  is  always 
exerted  between  different  kinds  of  matter.*  A  bar  of  iron, 
for  example,  is  held  together  by  cohesion,  and  is  attracted  to 
the  earth  by  gravitation;  but  when  the  iron  is  moistened,  the 
oxygen  of  the  water,  a  very  different  substance  from  iron, 
unites  with  it  and  forms  iron  rust.  This  is  effected  by  chem- 
ical affinity.  So  in  the  common  soda  powders,  the  tartaric 
acid  and  the  soda,  two  different  kinds  of  substances,  combine 
by  the  force  of  chemical  affinity.  Various  kinds  of  matter 
possess  this  attraction  with  different  degrees  of  force ;  thus, 
in  the  soda  powders,  the  soda  is  combined  by  affinity  to  car- 
bonic acid,  but  the  tartaric  acid  has  a  stronger  attraction  for 
the  soda  than  the  carbonic  acid  has,  and  displaces  it;  the 
liberated  gas  passes  up  through  the  water,  and  gives  rise  to 
the  foam  and  eflfervescence  which  is  so  desirable  and  grate- 
ful, when  such  waters  are  used  as  a  drink.  This  is  some- 
times called  elective  affinity,  and  gives  rise  to  all  the  decom- 
positions of  matter.  It  will  be  readily  perceived,  that  this 
agent  must  exert  great  influence  in  the  phenomena  of  vege- 
tation.    The  soil  itself  is  composed  of  substances  united  by 


*  See  Introduction. 


AGENCY  OF  AFFINITY.  101 

chemical  affinity.  All  the  decompositions  and  recomposi- 
tions,  which  take  place  in  its  mineral  ingredients,  and  in  the 
vegetable  and  animal  manures  are  due  to  this  power.  Hence, 
it  is  active  in  dissolving  the  rocks,  in  forming  saline  com- 
pounds, and  in  converting  manures  into  vegetable  food.  The 
nutriment,  it  is  supposed  by  some,  is  held  in  solution  in  water 
by  this  same  force.  The  sap  itself  is  prepared  for  the  pro- 
cess of  assimilation,  and  even  in  this  process,  that  is,  in  form- 
ing the  various  vegetable  products,  affinity  exerts  a  constant 
agency,  although  controlled  by  the  vital  power,  and  made 
subservient  to  it. 

Most  of  the  substances  which  are  added  to  the  soil  owe 
their  utility  to  the  changes  which  this  power  produces,  espe- 
cially the  application  of  saline  manures,  such  as  lime,  potash, 
ashes,  etc.  by  which  woody  fibre  is  decomposed,  metallic 
salts  and  acids  neutralized,  and  their  injurious  properties  de- 
stroyed and  converted  into  nutriment. 

So  many  are  the  changes  in  the  process  of  vegetation  which 
are  purely  chemical,  or  due  to  affinity,  that  some  chemists 
have  attempted  to  solve  the  mystery  of  life  itself  by  this  force, 
and  hence  have  discarded  the  idea  of  any  other  vital  power. 
It  doubtless  ranks  next  in  importance  to  the  vital  principle  it- 
self, and  is  employed  by  it  in  nearly  all  the  organic  changes, 
through  which  the  plant  passes  from  the  seed  to  mature  growth. 

IV.  Caloric.  The  influence  of  heat  in  vegetation  is  well 
known,  but  the  precise  manner  in  which  it  accomplishes  its 
beneficial  or  injurious  effects,  may  need  some  further  illus- 
tration. 

Heat  or  caloric  exists  in  two  states,  sensible,  or  the  heat  of 
temperature,  and  insensible,  or  in  a  state  incapable  of  affect- 
ing the  senses.  The  tendency  of  caloric  to  pass  from  one  of 
these  states  to  the  other,  as  the  forms  of  matter  change,  is 
one  of  the  most  important  properties  to  consider,  in  its  rela- 
tions to  vegetation.     A  second  property  is  its  tendency  to  ex- 

9 


102  BIOLOGY  OF  PLANTS. 

pand  all  bodies,  gaseous,  liquid  and  solid ;  and  a  third  is,  its  in- 
fluence on  affinity. 

1.  Its  influence  on  affinity  is  due  to  its  solvent  and  volati- 
lizing properties.  By  its  accumulation  in  bodies,  it  destroys 
cohesion  and  dissolves  or  melts  them,  and  brings  their  parti- 
cles into  contact,  so  as  to  produce  chemical  combinations  ;  or 
else  it  volatilizes  the  bodies,  and  removes  the  particles  from  the 
influence  of  each  other's  attractions.  In  these  ways  it  aids  or 
retards  the  decompositions  and  recompositions  in  the  soil,  and 
becomes  a  powerful  agent  in  preparing  the  proper  food  of 
plants. 

2.  The  effect  of  heat  in  the  spring  and  summer  is  to  ex- 
pand the  tubes  or  vessels  of  vegetables,  in  which  the  sap  cir- 
culates, and  also,  if  not  too  great,  to  render  the  juices  more 
fluid.  It  thus  promotes  a  more  easy  introduction  of  sub- 
stances into  the  roots,  and  a  more  rapid  circulation  through 
the  stems,  branches  and  leaves. 

But  if  the  heat  is  too  great,  which  often  happens  during 
dry  seasons,  when  neither  rain  nor  dew  is  sufficient  to  coun- 
teract its  effects,  the  juices  become  thickened,  and  the  vessels 
contracted ;  the  plant  shrivels  up,  and  often  wilts  and  dies. 
This  effect  would  be  produced  more  frequently,  were  it  not, 

3.  For  the  tendency  of  heat  to  pass  into  an  insensible  state 
in  the  process  of  evaporation  of  water  from  the  soil,  and  from 
the  plant  itself,  and  were  not  the  plant  otherwise  protected, 
from  extremes  of  temperature. 

The  fluids,  which  pass  into  the  plant,  are  some  of  them 
converted  into  solids  by  assimilation.  This  process  increases 
the  temperature  of  the  plant,  by  rendering  hisc7isihlc  caloric 
sensible,  and  is  a  means  of  heat,  when  sufficient  quantities 
from  without  are  not  supplied.  But  the  greater  part  of  the 
water,  which  enters  the  root,  is  thrown  out  or  transpired  by 
the  leaves,  and  other  green  parts.  The  moisture  thus  thrown 
out  upon  the  outer  surface,  by  passing  into  vapor,  absorbs  the 
sensible  and  external  heat.     The  higher  the  temperature,  the 


INFLUENCE  OF  CALORIC.  103 

more  rapidly  will  the  water  evaporate ;  thus  the  influence  of 
external  temperature  is  modified,  and  the  vital  powers  pre- 
served. 

The  quantity*  of  water  thus  transpired  amounts,  in  some 
cases,  to  the  weight  of  the  plant  in  twenty-four  hours. 

The  outer  or  upper  surface  of  the  leaf  is  further  protected, 
both  from  the  too  excessive  heat  of  the  sun's  rays  and  from 
the  agency  of  water,  by  a  thin  lining  of  silica  (flint),  which 
reflects  the  rays.  This  is  particularly  the  case  with  herba- 
ceous plants  or  grasses ;  the  epidermis  or  outer  coat  of  the 
stalks  and  leaves  being  composed  in  part  of  this  substance. 

The  temperature  of  the  atmosphere  is  kept  cool  in  the 
spring,  by  the  heat  which  is  required  to  convert  the  snow  and 
ice  into  water,  and  the  water  into  vapor.  The  process  of 
evaporation  moderates  the  temperature  during  the  summer 
months,  and  the  condensation  of  vapor  in  the  autumn  gives 
out  heat  to  the  air,  while  its  conversion  into  ice  and  snow 
still  further  moderates  the  approach  of  winter. 

In  this  way,  the  vegetable  kingdom  is  preserved  from  the 
extremes  of  heat  and  cold,  and  from  those  sudden  transitions 
which  might  otherwise  injure  or  destroy  it.    See  page  35. 

4.  During  the  winter,  the  roots  of  vegetables,  of  grasses 
and  trees  are  preserved  from  excessive  cold,  by  the  non-con- 
ducting properties  of  snow  and  ice.  The  surface  being  fro- 
zen, the  heat  of  the  earth  is  retained,  and  the  principle  of  vi- 
tality guarded  from  injury.  The  conversion  of  the  juices  of 
the  plant  into  ice  does  not  take  place  until  a  low  temperature 
is  reached.  When  this  happens  it  developes  its  latent  caloric, 
and  the  temperature  of  the  tree  from  this  source  must  be,  up- 
on'an  average,  above  that  of  the  surrounding  atmosphere. 

By  the  variations  of  temperature,  winds  are  produced,  and 
the  moisture  precipitated  to  the  earth  in  the  form  of  dew  and 
rain.  By  these  golden  showers  the  processes  of  vegetation 
are  carried  forward  and  enables  the  earth  to  yield  her  increase. 

*  See  Dana's  Muck  Manual,  p.  225. 


104 


BIOLOGY  OF  PLANTS. 


These  laws,  by  their  wise  constitution  and  their  constancy,  aid 
in  fulfilling  the  decree  of  heaven,  that  while  the  earth  remains, 
seed  time  and  harvest,  summer  and  winter,  cold  and  heat, 
shall  not  fail. 

Finally.  The  distribution  of  plants  over  the  surface  of 
the  earth  is  governed  more  by  temperature  than  by  any  other 
circumstance.  It  is  well  known  that  each  species  of  plants 
has  its  natural  limit.  This  is  particularly  true  of  the  food- 
bearing  plants;  and  their  agricultural  limits  are  principally 
determined  by  temperature  and  moisture.  The  northern 
agricultural  limits  are  bounded  by  lines  passing  through  places 
of  equal  summer  heat  and  are  called  isotheral  lines. 

The  southern  agricultural  limits  are  bounded  by  similar 
lines  of  equal  winter  heat,  and  are  called  isochimenal  lines. 
These  lines  are  exceeding  tortuous  in  their  course  around 
the  earth.  Thus  barley,  the  grain  which  has  been  cultivated 
farthest  north,  has  its  extreme  limit  in  the  Shetland  Islands, 
61°  N. ;  in  the  Feroe  Islands,  61°— 62^^°  N. ;  Lapland,  70°  N. ; 
near  the  White  Sea,  between  67°  and  80°  N. ;  in  Eastern  Rus- 
sia, about  66°  N. ;  and  in  Central  Siberia,  between  58°  and 
59°  N.  In  North  America  the  line  is  probably  similar.  The 
limit  for  the  potato  extends  a  little  farther  north.  Now  it 
is  found  that  this  line  passes  through  places  of  equal  summer 
temperature,  the  mean  of  which  is  from  46°  to  47°. 

Or  if  a  similar  examination  of  the  northern  limits  of  wheat 
be  made,  it  will  be  found,  that  equal  summer  temperature  is 
the  condition  of  the  limit.  This  is  in  latitude  64°,  and  the 
average  summer  temperature  57.4°  F.  This  limit  coincides 
with  that  of  fruit-trees,  apples,  pears,  and  also  of  the  oak.  Other 
grains  have  similar  isotheral  lines  which  limit  their  northern 
cultivation. 

If  now  we  turn  to  the  equatorial  regions,  we  shall  find  that 
the  limits  are  governed  by  equal  winter  temperature ;  for  it  is 
found  that  extreme  heat  arrests  the  cultivation  of  the  grains. 
The  temperature  for  germination  must  not  exceed  120  de- 


AGENCY  OF  LIGHT.  105 

grees.  This  limit  is  about  20°  N.  latitude.  The  southern 
limit  of  barley  is  farthest  north,  after  which  wheat,  then  rye, 
and  farthest  south,  Indian  corn.  Near  the  southern  limit,  as 
in  Bengal,  ''  Wheat,  barley  and  oats  are  sown  in  the  autumn, 
and  harvested  in  March ;  while  rice  and  maize  are  sown  in 
May,  to  be  harvested,  as  with  us,  in  October." 

It  is  the  same  condition  of  temperature,  which  limits  the 
cultivation  of  the  food-bearing  plants  on  mountains.  Thus, 
in  the  Alps  the  grains  cease  growing  at  the  following  heights : 

Wheat  at  3,400  feet,  corresponding  to  latitude  64  degrees. 
Oats  3,500  "  "  65       " 

Rye  4,600  "  «  67       " 

Barley       4,800  "  "  70       " 

The  above  facts  show  the  indispensable  agency  of  heat  up- 
on the  vital  power,  and  should  lead  the  farmer  to  adapt  his 
crops  to  its  influence,  as  affected  by  the  location  of  the  farm 
and  the  character  of  the  soil. 

V.  Light.  Light  has  been  shown  to  consist  of  three 
kinds  of  rays.  1.  Colorific,  or  those  rays  which  give  color 
to  the  various  objects  in  nature.  2.  Calorific,  or  those  rays 
which  produce  heat,  and  are  the  cause  of  the  sun's  warmth. 
3.  Chemical  rays,  or  those  which  produce  effects  upon  chemical 
combinations.  These  rays  are  easily  separated  by  means  of 
a  prism.  Whether  the  effect  upon  vegetation  results  from  a 
combination  of  all  the  rays,  or  is  produced  by  one  kind,  is 
not  certainly  known ;  but  the  probability  is  that  the  power,  in 
this  respect,  depends  partly  upon  the  chemical  rays,  and  part- 
ly upon  the  colorific  rays. 

1.  Light  is  a  powerful  stimulant  to  vegetation,  changing 
the  color  of  the  leaves  and  stalks,  and  giving  the  pungent  pro- 
perties peculiar  to  each  species  of  plant.  Those  vegetables 
which  grow  in  the  shade  are  always  pale  and  sickly  in  growth, 
and  insipid  in  taste.  But  let  a  ray  of  light  cross  the  stem  or 
leaf  of  such  a  plant,  and  it  will  turn  green  in  that  spot,  and 
become  pungent,  although  all  other  parts  remain  as  before. 
9* 


106  BIOLOGY  OP  PLANTS. 

2.  But  the  most  direct  agency  of  light  is  seen  in  the  pow- 
er which  it  gives  to  the  leaves,  to  decompose  the  carbonic 
acid,  and  prepare  the  juice  for  the  processes  of  assimilation. 
Plants  which  grow  in  the  dark  do  not  possess  this  power,  and 
hence  the  acid  remains  in  the  juices,  and  the  carbon  is  but 
feebly  assimilated.  We  can  see  the  reason  why  vegetation 
is  more  flourishing  in  the  torrid  zone ;  there  is  a  greater 
quantity  of  light  there.  But  each  plant  seems  to  have  a  con- 
stitution peculiar  to  itself  in  this  respect ;  some  being  able  to 
flourish  better  in  the  shade  than  others.  There  are  some  kinds 
of  grasses,  and  many  flowers  which  will  flourish  best  in  the 
shade,  while  others  require  to  be  exposed  to  all  the  light  there 
is,  and  if  the  natural  quantity  is  not  supplied,  will  wilt  and 
die. 

3.  The  different  effects  produced  by  rays  of  different  colors 
has  been  pointed  out  by  Mr.  Hunt.  In  his  experiments, 
cress  seeds  were  exposed  in  the  soil  to  the  action  of  the 
red,  yellow,  green  and  blue  rays,  which  were  transmitted 
through  equal  thicknesses  of  colored  infusions.  "  After  ten 
days,  there  was,  under  the  blue  fluid,  a  crop  of  cress  of  as  bright 
a  green  as  any  which  grew  in  full  light,  and  far  more  abun- 
dant. The  crop  was  scanty  under  the  green  fluid,  and  of  a 
pale,  yellow,  unhealthy  color.  Under  the  yellow  solution, 
only  two  or  three  plants  appeared,  but  less  pale  than  those 
under  the  green  ;  while  beneath  the  red,  a  few  more  plants 
came  up  than  under  the  yellow,  though  they  also  were  of  an 
unhealthy  color.  The  red  and  blue  bottles  being  now  mu- 
tually transferred,  the  crop  formerly  beneath  the  blue  in  a 
few  days  appeared  blighted,  while  on  the  patch  previously  ex- 
posed to  the  red,  some  additional  plants  sprang  up." 

The  necessity  of  light  to  the  health  and  vigor  of  plants,  is 
a  matter  of  daily  observation.  They  seem,  as  it  were,  to  be 
endowed  with  a  kind  of  instinct  for  it.  How  constantly  do 
many  leaves  follow  the  sun  in  his  daily  course  !  What  count- 
.less  numbers  of  blossoms  close  and  drop  when  he  retires  at 


AGENCY  OF  ELECTRICITY.  107 

night,  and  turn  their  faces  as  if  eager  to  catch  the  first  rays 
of  the  morning  ! 

VI.  Electricity.  Electricity  is  a  much  more  subtle 
agent  than  any  which  have  been  named ;  and  although  the 
mode  in  which  it  produces  its  effects  is  not  so  easily  discov- 
ered, yet  from  some  experiments  it  is  rendered  probable,  that 
its  action  is  nmch  more  direct  and  efficient  upon  the  vital 
functions  of  plants,  than  has  been  commonly  supposed.  It 
seems  to  be  widely  disseminated  throughout  the  atmosphere, 
the  water,  and  the  soil. 

Electricity  is  developed  by  friction,  and  by  chemical  ac- 
tion. The  former  is  called  common^  the  latter  Voltaic  elec- 
tricity, or  Galvanism.  Change  of  temperature  and  of  form 
develope  it,  the  condensation  of  vapor,  the  variations  of 
temperature  in  the  atmosphere,  and  the  chemical  changes, 
which  take  place  in  the  soil,  are  constant  sources.  The  na- 
ture of  the  electric  fluid  is  unknown. 

Theory.  It  is  supposed  to  consist  of  two  fluids  pervading 
all  matter  ;  the  one  is  called  positive  or  vitreous  ;  the  other, 
negative  or  resinous.  Each  repels  itself,  and  attracts  the  op- 
posite.* Acids  are  generally  negative,  and  alkalies  positive; 
hence,  the  electric  state  of  the  soil  may  generally  be  known 
by  its  composition. 

If  a  soil  is  wholly  negative,  as  is  the  case  with  pure 
silica  or  sand ;  or  wholly  positive,  as  is  the  case  with  alumi- 
na, lime,  magnesia,  iron  and  the  alkalies,  it  is  always  wholly 
barren ;  or  when  one  ingredient  greatly  predominates,  it  is 
unfavorable  to  vegetation ;  and  the  object  of  amendments  is 
to  bring  the  soil  to  a  neutral  state.f  The  animal  and  vege- 
table substances  in  the  soil  produce  acids  and  alkalies,  which 
develope  by  their  affinities  electrical  currents.  The  soil,  be- 
ing composed  of  different  minerals,  and  saturated  with  mois- 
ture,constitutes  a  galvanic  battery,  which  is  constantly  acting 
upon  the  functions  of  vegetables,  and  upon  the  rocks. 

*  See  Gray's  Chemistry,  p.  74.  t  See  '  Soils,'  chap.  5th. 


108 


BIOLOGY  OF  PLANTS. 


That  the  electrical  powers  thus  developed  must  exert  a 
constant  and  powerful  agency  upon  the  growth  of  plants,  ap- 
pears from  the  fact,  that  electricity  is  a  most  efficient  pro- 
moter of  endosmosc  or  absorption.  Endosmose  is  a  term, 
which  Mons.  Dutrochet  has  given  to  a  peculiar  power  which 
he  discovered  in  experimenting  upon  the  permeability  of  tis- 
sues. Its  name  is  from  the  Greek,  and  signifies  intei-nal  im- 
pulse. It  seems  to  be  a  property  possessed  by  all  thin,  mem- 
branous substances,  when  liquids  of  different  densities,  and 
electro-motive  powers  are  placed  on  each  side  of  the  mem- 
brane. The  following  is  a  mechanical  illustration  of  this  cu- 
rious property. 

Fig.  13  represents 
the  endosmometer.  It 
consists  of  a  small  bell- 
glass  receiver  a,  with 
a  glass  tube  c,  open  at 
both  ends,  and  accu- 
rately fitted  to  the  ap- 
erture in  the  top  c. 
Over  the  mouth  of  the 
receiver  is  stretched 
any  membrane,  as  a 
fresh  bladder ;  and  a 
metallic  substance,  e- 
ven  and  firm, with  aper- 
tures punched  through 
it,  is  placed  upon  the 
membrane  as  a  support.  The  receiver  may  then  be  filled 
with  sweetened  water,  molasses,  or  almost  any  substance 
denser  than  water,  through  the  cork  c.  The  receiver  must 
now  be  placed  in  a  vessel  of  water  6,  so  that  the  water  on  the 
outside  of  the  receiver  shall  be  at  the  same  height  with  the 
substance  within.  If  now  this  is  suffered  to  remain,  the  mem- 
brane will  draw  in  the  water,  and  force  it  up  the  tube,  as 


AGENCY  OF  ELECTRICITY.  109 

d.  The  force  thus  exerted  by  the  membrane  is  equal  to  the 
weight  of  the  atmosphere,  as  it  vvouJd,  in  time,  raise  the  col- 
umn of  water  thirty-two  feet  in  height.  If  now  P,  the  posi- 
tive wire  of  a  galvanic  battery,  is  immersed  in  the  water,  and 
n,  the  negative  wire  communicate  with  the  interior  through 
the  cork  e,  the  effect  will  be  greatly  increased  ;  and,  if  the 
wires  are  reversed,  the  liquid  in  the  receiver  may  be  made  to 
flow  out  into  the  vessel  of  water. 

According  to  the  experiments  of  Dutrochet,  the  ascensional 
force  in  this  instrument  is  about  equal  to  the  pressure  of  the 
atmosphere ;  and  Mirbel  found  the  ascensional  power  of  the 
sap  in  a  grape-vine  to  be  the  same  as  in  this  instrument.  By 
cutting  off  a  grape-vine,  and  adapting  to  it  a  glass  tube  filled 
with  mercury,  the  outpouring  of  the  sap  will  raise  the  mercury 
twenty-eight  inches  in  the  tube. 

If  now  we  examine  the  spongioles  of  vegetables,  we  shall 
find,  that  each  has  a  bladder  which  stands  out  to  absorb  the 
nutritious  particles ;  and  that  the  tubes  are  filled  with  mem- 
branes, in  which  the  endosmometric  action  is  produced.  The 
fluids  constituting  the  sap  are  generally  denser  than  water,  a 
circumstance  which  is  esssential  to  the  action.  If  we  sup- 
pose currents  of  electricity,  developed  in  the  soil,  to  be  passing 
through  the  tubes  of  the  vegetable,  we  have  perhaps  the  most 
satisfactory  theory  of  the  ascent  of  the  sap*  which  can  be 
furnished.  Hence  it  appears  that  one  prominent  object  of 
the  agriculturist  is  to  balance  the  electrical  forces  in  his  soil, 
in  order  that  the  highest  effect  of  this  power  may  be  produced 
upon  his  crops.     There  appears  also  to  be  an  opposite  move- 

*  As  the  ascent  of  the  sap  may  thus  be  accounted  for  on  mechanical 
and  electrical  principles,  it  may  be  thought  that  this  example  is  op- 
posed to  the  views  respecting  the  vital  principle^  which  were  present- 
ed in  the  first  chapter.  But  it  should  be  remembered,  that  the  effect 
here  depends  upon  the  tissue  or  membrane  which  is  a  product  of  vital- 
ity. How  can  chemical  laws  construct  the  spongelets,  and  the  mem- 
branes, which  must  be  placed  across  the  tubes  in  which  the  sap  cir- 
culates .'' 


110 


BIOLOGY   OF  PLANTS. 


ment  in  theendosmometer,  but  the  liquid  passes  out,  in  much 
less  quantities  than  it  passes  in.  This  movement  is  called 
exosmose,  and  may  illustrate  the  process  of  transpiration,  or 
perhaps  favor  the  theory  that  plants  excrete  nourishment  into 
the  soil,  unfitted  for  their  own  species,  but  capable  of  nourish- 
ing those  of  a  different  family. 

The  influence  of  electricity  upon  germination,  according 
to  Davy,  is  to  increase  the  vital  energies.  He  found  that 
corn  sprouted  more  rapidly  in  water  positively  electrified  by 
the  voltaic  battery,  than  in  water  negatively  electrified.  We 
should  suppose,  from  analogy,  that  electricity  would  exert  a 
powerful  influence  upon  the  vital  power  of  vegetables,  from 
its  known  influence  upon  this  power  in  minerals.  In  medi- 
cine, it  has  long  since  been  employed  as  a  remedy,  especially 
to  restore  sensation  to  parts  which  have  become  deprived  of 
feeling.  Some  experiments  seem  to  prove,  that  continued 
voltaic  action  upon  animals  of  microscopic  dimensions,  so 
excites  and  quickens  the  vital  power,  as  to  increase  their 
growth  a  thousand  fold ;  thus,  converting  animalculae,  which 
are  too  small  to  be  seen,  into  visible  and  tangible  insects. 
This  fact  has  led  some  men  even  to  adopt  the  hypothesis, 
that  they  were  created  by  this  power,  that  the  vital  and 
electrical  powers  were  identically  the  same,  and  that  the  pro- 
cess of  life  is  carried  forward  by  a  galvanic  battery,  consist- 
ing principally  of  the  brain  and  nervous  system. 

As  vegetables,  however,  are  not  sensitive  beings,  it  is 
more  difficult  to  trace  in  them,  the  influence  of  this  agent ; 
but  enough  is  known  to  infer  its  utility,  and  perhaps  neces- 
sity to  the  existence  of  the  vegetable  kingdom. 

Sect.  4.  Agency  of  Man. 

There  is  but  one  remaining  agent  required  for  the  most 
vigorous  action  of  the  vital  principle,  and  that  is  the  farmer 
himself.     The  vital  power  may  exist  in  the  seed,  but  it  will 


AGENCY  OF  MAN.  Ill 

not  develope  itself  without  his  care  and  skill.  He  cannot  act 
directly  upon  the  functions  of  plants,  as  the  other  agents  do, 
but  he  can  modify,  and,  to  a  certain  extent,  control  the  influ- 
ence of  those  agents.  He  must  learn  the  conditions  required 
for  their  beneficial  action.  He  is  the  overseer,  who  brings 
together  natural  powers,  that  they  may  act  usefully  upon 
each  other,  and  upon  the  materials  which  are  to  be  manufac- 
tured. And  although  his  agency  is  secondary,  still  it  is  not 
less  necessary  or  beneficial,  than  if  he  could  cause  his  crops 
to  grow  by  direct  power ;  for  although  the  agents  we  have 
described,  act  with  their  own  efficiency,  and  according  to 
their  own  fixed  laws,  still  they  are  under  the  control  of  the 
farmer,  to  a  much  greater  extent  than  he  supposes. 

In  reference  to  the  vital  power  itself,  we  have  already  seen 
the  agency  of  the  farmer  :  he  must  supply  it  with  certain  con- 
ditions, proper  food,  soil,  tillage,  etc.  before  he  can  expect  a 
bountiful  crop.  The  other  agents  are  perhaps  less  under 
his  control,  and  it  may  be  asked  by  some,  of  what  use  a  de- 
scription of  them  can  be  to  a  practical  farmer.  On  the  sup- 
position that  the  atmosphere,  water,  light,  heat  and  electrici- 
ty, do  exert  all  the  influence  which  is  claimed  for  them,  are 
they  not  beyond  the  control  of  man  ?  How  can  the  farmer 
make  the  sun  shine  warmer  or  brighter,  or  the  rains  and 
dews  descend  in  greater  or  less  quantities  ?  How  can  he 
control  those  mysterious  powers  of  electricity  and  aflSnity, 
whose  universal  agency  is  witnessed  by  all  ?  These  inquiries 
arise  from  an  erroneous  idea  of  the  case,  from  a  false  idea  of 
the  processes  above  named.  It  is  because  these  agents  are 
under  the  control  of  the  farmer,  not  directly  but  incidentally, 
that  they  are  brought  forward  for  his  consideration.  Their 
agency  is  not  a  matter  of  mere  science,  but  of  practical  utili- 
ty, of  vast  importance  to  every  man  who  attempts  to  cultivate 
even  a  garden. 

1.  The  atmosphere  and  its  contents.  How  can  the  farmer 
employ  this  agent  1     He  can  secure  its  agency  by  so  prepar- 


112  BIOLOGY  OF  PLANTS. 

ing  and  tilling  his  soil  that  its  moisture,  carbonic  acid,  oxy- 
gen and  other  constituents,  may  circulate  freely  through  it, 
to  all  parts  of  the  roots.  By  giving  to  the  soil  a  proper  con- 
sistency, and  by  supplying  it  with  vegetable  and  mineral  sub- 
stances, the  elements  of  the  atmosphere  are  made  to  act  upon 
the  vital  functions  with  greater  power.  Thus,  by  giving  to 
the  soil  greater  absorbing  power,  it  will  feel  the  influence  of 
the  dews ;  by  draining  it,  the  injurious  effects  of  water  will 
be  prevented,  and  the  action  of  the  air  facilitated.  If,  there- 
fore, the  farmer  cannot  cause  the  rains  and  dews  to  descend  at 
his  will,  he  can  so  prepare  the  soil  that  the  highest  advantage 
may  result  from  the  influence  of  these  agents. 

2.  The  influence  of  heat.  How  can  this  agent  be  applied 
by  the  farmer  ?  Simply  by  adding  to  the  soil,  mineral  or  vege- 
table substances,  which  will  give  it  the  power  of  absorbing 
and  retaining  the  heat  of  the  sun,  or  which  will,  by  their  com- 
binations, produce  heat  in  the  soil.  By  the  fermentation  of  ma- 
nures, great  quantities  of  heat  are  given  out ;  hence,  if  the 
soil  is  naturally  cold,  manures  should  be  applied  before  they 
are  fermented,  and  incorporated  with  the  soil  that  the  heat 
may  be  equally  distributed.  By  increasing  the  fertility  of  the 
soil,  its  power  of  retaining  heat  will  be  increased. 

3.  Electricity.  How  is  the  influence  of  this  agent  con- 
trolled by  the  farmer  ?  If  a  soil  is  acid,  that  is,  in  a  state  of 
negative  electricity,  it  is  wholly  barren  ;  if  a  soil  is  alkaline, 
that  is,  in  a  positive  state  of  electricity,  it  is  also  barren  ;  but 
when  its  acids  are  neutralized  by  its  alkalies,  then  it  is  in  a 
state  favorable  to  fertility,  and  the  more  completely  the  elec- 
tro-powers of  the  soil  are  balanced,  the  more  fertile  will  the 
soil  become.  Now,  by  analysis,  the  electrical  state  of  the  soil 
can  be  determined,  and  the  substance  applied  which  will  re- 
store the  equilibrium  of  the  electric  forces.  From  the  analy- 
sis of  soils  of  different  degrees  of  fertility,  it  is  surprising  to 
notice  how  narrow  the  limits  are,  between  absolute  barren- 
ness and  a  high  state  of  fertility.     One  soil,  for  example, 


AGENCY  OF  MAN.  113 

which  is  wholly  barren,  may  have  its  fertility  restored  by  the 
addition  of  one  per  cent,  of  lime,  or  even  a  few  bushels  to  the 
acre.  Another,  which  is  acid,  and  therefore  unfavorable  to 
vegetation,  may  by  the  addition  of  a  single  grain  in  a  hun- 
dred of  some  alkali,  be  made  to  yield  forty,  fifty,  or  a  hundred 
fold. 

Many  a  farm  has  remained  for  years  barren,  because  its 
electrical  forces  were  not  properly  balanced,  while  the  addi- 
tion of  some  well-known  substance,  perhaps  in  the  proportion 
of  not  more  than  one  grain  in  a  million,  would  restore  it  to 
fertility.  It  is  said  by  certain  medical  practitioners,  that  a 
millionth  part  of  a  grain  of  arsenic  or  opium,  will  act  with 
better  effect  upon  certain  diseases,  than  much  larger  quanti- 
ties. This  doctrine  of  the  homoeopathist,  applies  with  per- 
fect truth  to  the  application  of  certain  salts  to  the  soil.  It  is 
often  surprising  to  notice  the  effect  of  a  single  grain  of  lime 
or  potash  in  a  hundred  of  the  soil,  doubling,  tripling,  and  of- 
ten quadrupling  the  quantity  of  the  productions  in  a  single 
year.  This  result  must  be  due,  in  part,  to  the  electrical  ef- 
fect which  this  small  addition  produces  ;  hence  we  may  learn 
both  the  importance  of  ascertaining  the  composition  of  soils 
by  accurate  analysis,  and  of  improving  them  by  adding  those 
substances  which  they  require. 

In  conclusion,  it  may  be  remarked,  that  the  agents,  consid- 
ered in  this  and  the  preceding  chapter,  are  not  only  the  great 
causes  of  change  and  reproduction  in  the  vegetable,  but  also  in 
the  animal  and  mineral  kingdoms.  Most  of  them  are  the  natu- 
ral powers  ordained  of  God  for  the  government  of  the  natural 
world.  A  correct  knowledge  of  them  will  help  us  to  explain 
the  almost  infinitely  varied  and  mysterious  phenomena  which 
are  every  day  presented  to  our  minds ;  and  when  we  have 
begun  to  understand  their  agency,  when  we  can  trace  the 
chain  of  effects  to  the  ultimate  cause  we  shall  find,  that  they 
will  present  subjects  of  deep  and  delightful  reflection. 

They  will  enable  us  to  gain  a  deeper  and  more  profitable 
10 


114  BIOLOGY  OF  PLANTS. 

insight  into  the  mysteries  of  nature,  and  to  be  better  fitted  to 
discharge  our  duties  as  citizens  and  as  men  ;  our  toils  will 
become  lighter,  because  we  shall  find  in  our  employment  an 
interest  and  a  soul. 


9 


CHAPTER  III. 

PRODUCTIONS  OF    THE    VITAL   PRINCIPLE THEIR  CHARACTER, 

COMPOSITION,  SOURCES  AND  ASSIMILATION. 

Having  in  the  preceding  chapters  given  a  general  account 
of  the  vital  principle,  and  the  agents  which  act  upon  it,  in- 
cluding the  general  processes  of  vegetation,  we  come  now  to 
describe  the  productions  of  this  power ;  for,  in  opposition  to 
the  views  of  many  chemists  and  vegetable  physiologists,  we 
still  insist,  that  this  power  actually/  ensts  in  vegetables,  and 
that  we  have  good  reasons  for  ascribing  to  it,  as  a  principal 
agent,  the  various  compounds  which  are  found  in  vegetable 
bodies.  The  character  of  these  compounds  is  wholly  differ- 
ent from  that  produced  by  a  chemical  or  a  mechanical  agent. 
Their  composition  cannot  be  accounted  for  by  ordinary  chem- 
ical changes  ;  and  the  source  and  assimilation  of  their  simple 
constituents,  teach  the  same  doctrine.  This  chapter,  there- 
fore, will  be  devoted  to  the  discussion  of  these  topics. 

Sect.  1.  Character  and  Composition  of  the  Vegetable  Pro- 
ductions. 
The  productions  of  the  vital  power  are  very  numerous. 
They  are  called  vegetable  or  proximate  principles,  such  as 
sugar,  gum,  and  starch ;  and  differ,  materially,  in  their  char- 
acter and  composition,  from  inorganic  bodies.  The  vegetable 
principles  exist  in  plants,  already  formed  ;  and  the  processes 
by  which  they  are  separated,  are  called  proximate  analysis. 


PRODUCTIONS  OF  THE  VITAL  PRINCIPLE.  115 

These  processes  are  various,  and  are  described  in  works  on 
elementary  chemistry.  Many  of  them,  however,  are  well 
known  to  farmers,  such  as  the  obtaining  of  starch  from  pota- 
toes or  wheat,  of  sugar  from  the  juice  of  the  maple,  beet-root, 
etc.  The  vegetable  proximate  principles  are  all  decomposed 
by  a  red-heat,  and  are  converted  chiefly  into  carbonic  acid 
and  water.  When  subjected  to  ultimate  analysis,  they  are 
found  to  be  composed  of  carbon,  oxygen,  hydrogen  and  nitro- 
gen. Small  quantities  of  phosphates,  sulphates,  metallic  ox- 
ides and  earths  are  found  in  vegetable  bodies ;  which,  though 
essential  to  them,  constitute  but  a  small  portion  of  their  sub- 
stance, and  are  called  the  inorganic  constituents  of  plants. 
The  vegetable,  as  it  is  formed  in  nature,  contains  alkalies 
and  metallic  oxides,  in  combination  with  ihe  proximate  prin- 
ciples, although  the  latter,  as  such,  contain  no  metallic  bases. 

The  simple  bodies  O.  C.  H.  N.  are  found  combined  in  va- 
rious proportions.  Generally  a  larger  number  of  equivalents 
are  united  to  form  the  organic  than  the  inorganic  body. 
Some  organic  bodies  are  composed  of  two,  some  of  three, 
and  others  of  four  simple  bodies ;  and  the  proportions  vary 
from  one  to  seventy  equivalents  or  more,  but  in  inorganic 
bodies,  rarely  more  than  seven  equivalents  of  the  same  ele- 
ments are  found. 

I.  Organic  principles,  composed  of  two  ingredients,  are  of 
four  kinds. 

1.  Compounds  of  carbon  and  hydrogen,  as  in  oil  of  turpen- 
tine, which  is  composed  of  C'^H^,*  and  in  the  volatile  and 
fixed  oils. 

*  It  will  be  recollected  that  the  four  bodies,  carbon,  oxygen,  hydro- 
gen and  nitrogen,  are  represented  by  their  initial  letters,  C.  O.  H.  N. 
and  the  number  of  equivalents  are  represented  by  figures  placed  as  in- 
dices ;  thus  C^,  O^,  signifies  a  compound  formed  of  2  equivalents,  or  12 
parts  by  v/eight  of  carbon,  and  3  equivalents,  or  24  parts  by  weight 
of  oxygen.  The  equivalent  of  hydrogen  is  1,  oxygen  8,  carbon  6.12, 
and  nitrogen  14.  We  have  only  to  look  at  the  indices,  to  ascertain 
the  number  of  equivalents  in  any  compound,  and  by  multiplying  that 


116  BIOLOGY  OF  PLANTS. 

2.  Of  hydrogen  and  oxygen,  as  water,  which  is  formed  of 
OH. 

3.  Of  carbon  and  oxygen,  as  oxalic  acid,  composed  of 
C203. 

4.  Of  carbon  and  nitrogen,  as  cyanogen,  composed  of  C^N. 

II.  Oi'ganic  principles,  composed  of  three  constituents,  are 
much  more  numerous  than  the  preceding. 

1.  The  most  common  combinations  are  carbon,  hydrogen 
and  oxygen.  Sugar,  gum,  etc.  and  the  greatest  number  of 
acids,  are  thus  constituted. 

2.  Compounds  of  carbon,  hydrogen  and  nitrogen,  as  azul- 
mic  acid  which  is  thus  constituted,  C^HN^. 

3.  Compounds  of  carbon,  oxygen  and  nitrogen,  as  carba- 
zotic  acid,  CisN^O^s. 

III.  Organic  principles  of  four  constituents,  as  aspartic 
acid,  C^H^NO^.  Almost  all  the  alkalies  contain  these  four 
substances. 

Of  the  simple  substances,  carbon  is  most  abundant,  and 
next  are  oxygen  and  hydrogen ;  while  nitrogen,  although  not 
absent  from  any  part  of  a  plant,  exists  in  very  small  quan- 
tities in  all. 

But  the  substances  which  constitute  the  principal  mass  of 
every  vegetable,  are  compounds  of  oxygen  and  hydrogen  (in 
the  proportions  to  form  water)  and  of  carbon.  In  a  second 
class,  oxygen  is  in  excess,  as  in  the  numerous  organic  acids. 
In  a  third  class,  as  the  volatile  and  fixed  oils,  carbon  and  hy- 
drogen exist,  but  no  oxygen,  and  in  a  fourth  class  nitrogen 
is  added,  as  in  vegetable  albumen,  in  indifferent  substances, 
and  in  some  acids. 

by  the  number  represcnlinir  the  equivalent  for  that  substance,  the  ex- 
act amount  by  weight  may  be  obtained.  The  whole  added  together 
gives  the  equivalent  of  the  compound,  which  is  also  represented  by 
numbers.  This  mode  of  represention  is  now  adopted  by  all  chemical 
writers,  and  seems  useful  to  present  tlie  compounds  to  the  eye  in  a 
condensed  form. 


VEGETABLE  ACIDS.  117 

The  vegetable  principles  are  divided  by  Thompson  into 
the  four  following  classes. 

I.  Acids.  11.  Alkalies.  III.  Intermediate  bodies.  IV. 
Neutral  bodies. 

The  substances,  classed  under  these  heads,  are  not  all  the 
products  of  the  vital  principle.  Some  of  them  result  from  de- 
compositions, and  hence  are  the  products  of  death  rather  than 
of  life.*  A  large  number  of  the  products  of  vitality  are  in- 
serted in  this  section  as  a  convenient  reference  for  those  who 
have  not  better  sources  of  information.  The  agricultural 
reader  can  omit  them,  if  he  chooses,  altogether. 

I.  Acids.  The  number  of  acids,  derived  from  the  vegetable 
kingdom,  amount  to  116,  but  a  few  of  this  number  are  of  any 
particular  impoitance  to  agriculture.  The  following  are  the 
principal  vegetable  acids.  Oxalic,  citric,  tartaric,  benzoic,  me- 
conic,  acetic,  malic  and  prussic  acids.  All,  save  the  last  three 
which  have  been  obtained  only  in  a  liquid  state,  are  white  crys- 
taline  solids.  All  are  more  or  less  soluble  in  water.  All  are 
sour  to  the  taste,  with  the  exception  of  gallic  and  Prussic  acids, 
the  first  of  which  being  astringent,  and  the  latter  having  the 
taste  of  bitter  almonds. 

1.  Oxalic  acid  (€^03=36.24)1  is  found  in  wood  sorrel,  [Oxalis 
acetosella,)  and  is  the  cause  of  its  sour  taste.  It  also  exudes  from 
the  chic  pea  [deer  arietinum).  Many  vegetable  principles,  such 
as  gum,  starch,  etc.  are  converted  into  this  acid  by  nitric  acid. 
It  exists  in  small,  slender  crystals,  resembling  epsom  salts,  for 
which  it  is  sometimes  mistaken  with  fatal  consequences.  It  is 
a  powerful  poison  with  a  strong  acid  taste.  It  is  distinguished 
by  its  power  of  decomposing  all  salts  of  lime,  and  forming  with 
the  base  an  insoluble  salt.  This  acid  is  found  in  combination 
with  lime  [Oxalate  of  lime)  in  several  species  of  lichens.     When 

*  For  a  complete  description  of  all  the  vegetable  principles,  the  rea- 
der is  referred  to  Thompson's  Chemistry  of  Organic  Vegetable  Bodies. 

=1  The  expression,  020^=36,  when  translated,  would  read  thus : 
Oxalic  acid  is  composed  of  2  equivalents  of  carbon,  or  12.24  parts  by 
weight,  and  3  equivalents  of  oxygen,  or  24  parts  by  weight,  which 
makes  an  equivalent  of  oxalic  acid  equal  to  36.24 ;  that  is,  when  oxalic 
acid  combines  with  any  other  body,  it  always  unites  36  parts  by  weight. 

10* 


118  BIOLOGY  OF  PLANTS. 

first  precipitated,  the  oxalate  of  lime  (C^OSCaOSHO =82.74)  is  a 
snow-white,  floculent  powder. 

Oxalate  of  potassa*  is  commonly  called  the  tssential  salt  oj 
lemons,  and  is  used  to  remove  spots  and  iron  rust  from  linens. 

2.  Citric  acid  (C^H2O''=G0)  is  found  in  many  acidulous  fruits, 
such  as  limes,  lemons  and  oranges.  It  is  distinguished  by  form- 
ing an  insoluble  salt  with  lime,  and  is  used  in  preparing 
lemon  syrup. 

3.  Tartaric  acid  {^^11^0^=66.24:)  exists  in  acidulous  fruits, 
especially  in  the  juices  of  the  mulberry  and  grape,  usually  in 
combination  with  lime  or  potassa.  It  is  the  substance  used 
with  soda  for  an  effervescing  drink.  Bitarirate  of  potassa  is 
foimd  in  old  wine  casks,  and  when  purified,  is  called  cream  oJ 
tartar,  and  is  used  in  medicine.  Tartar  emetic  is  a  compound 
of  tartaric  acid  with  potassa  and  antimony,  and  is  neutralized 
by  astringents,  such  as  tea  or  Peruvian  bai"k,  in  case  too  large 
a  dose  is  taken. 

White  Rochelle  salt  is  formed  of  potassa  and  soda,  combined 
with  tartaric  acid. 

3.  Benzoic  acid  (C^^H503=123)  exists  in  gum  benzoin,  in 
the  balsams  of  Peru,  and  some  other  vegetable  substances.  It 
is  distinguished  by  its  volatility  and  aromatic  odor ;  although, 
when  perfectly  pure,  it  has  no  smell.  When  sublimed,  it  forms 
long,  flat,  prismatic  nodules,  having  a  beautiful  satin  lustre. 

4.  Meconic  acid  (C'^H20'''==  100,84)  is  found  in  the  poppy,  in 
combination  with  morphia,  and  crystalizes  in  white,  transj)arent 
scales. 

5.  Gallic  acid  (C'''H305=85)  is  found  in  gall-nuts  and  in  the 
bark  of  trees.  It  forms  ink  by  combining  with  the  proto-sul- 
phuret  of  iron. 

6.  Tannic  acid  (CiSH^Oi^^Qi^)  exists  also  in  gall-nuts,  in 
tea  and  vegetable  astringents,  and  is  the  cause  of  their  astrin- 
gency.  With  gelatine  or  glue  it  forms  an  insoluble  compound, 
which  is  the  basis  of  leather ;  hence  its  use  in  tanning  hides. 
Tannic  and  gallic  acids  possess  the  property  of  preserving 
bodies  from  decay. 

7.  Acetic  acid  (C^H303=51,48)  exists  in  the  sap  of  many 
plants.  It  is  well  known  under  the  name  o{  vinegar.  It  forms 
numerous  salts  with  inorganic  bases,  such  as  acetates  of  lead  {su- 

*  When  an  acid  combines  with  an  alkali  or  metallic  oxide,  the 
substance  formed  is  called  a  salt,  and  the  name  of  the  acid  changes  its 
termination  into  ate,  or  if  the  acid  terminate  in  ous,  into  ite. 


VEGETABLE  ALKALIES.  119 

gar  of  lead) ;  of  copper  (verdigris) ;  and  many  others,  which 
are  useful  in  the  arts. 

8.  Malic  acid  {C''H2O4=60)  is  obtained  from  the  juice  of 
apples,  barberrieSj  plums,  elder-lierries,  currants,  strawberries, 
raspberries,  etc.  It  is  distinguished  from  the  preceding  acids, 
by  forming  soluble  salts  with  lime. 

9.  Pnissic  acid  (C2NH=27)  is  obtained  by  the  distillation 
of  laurel  leaves,  from  the  stones  of  the  peach,  cherry,  and  bit- 
ter almonds.  This  is  the  most  violent  poison  with  which  we 
are  acquainted. 

The  above  are  only  a  few  of  the  vegetable  acids.  They  impart 
to  fruit  that  tart,  pleasant  taste  which  forms  their  distinguishing 
characteristic. 

II.  Alkcdies.  This  class  includes  about  thirty-seven  sub- 
stances, all  discovered  since  1817.  Those  plants  which  are 
remarkable  for  their  poisonous  or  medicinal  properties,  contain 
an  alkaline  principle.  Those  most  important  in  this  connec- 
tion are  Morphina,  Narcotina,  Cinchonina,  Quinina,  Strychni- 
na,  Emetina,  Nicotina,  Conicina,  Solanina,  Parillina.  They  are 
compounds  of  hydrogen,  oxygen,  carbon  and  nitrogen ;  and 
their  composition   will  be  indicated  by  symbols,  as  in  other 


1.  Morphina  {C^'^W^'NO^=2S4l)  is  the  narcotic  principle 
of  opium,  and  constitutes  about  -^\  of  its  weight.  It  is  a  well- 
known  poison,  of  an  astringent  bitter  taste.  It  is  used  in  medi- 
cine to  allay  pain.  When  opium  has  been  administered  as  a 
poison,  a  skilful  chemist  will  detect  a  single  grain  of  the  mor- 
phina in  700  grains  of  water.  It  is  contained  in  the  capsule  of 
the  poppy,  from  which  it  is  generally  obtained.  It  combines 
with  a  great  many  organic  and  inorganic  acids ;  and  the  salts, 
thus  formed,  are  used  extensively  in  medicine. 

2.  J^arcotina  (C^OH^ONOi^)  is  found  in  opium.  It  is  not  in- 
jurious to  man,  but  fatal  to  dogs ! 

3.  Cinchonina  (C20H'2NOl^=158)  is  found  in  Peruvian  bark 
{cinchona  nitida,  or  condaminea),  and  imparts  to  it  its  value  as  a 
medicine.  It  has  a  peculiar  bitter  taste,  which  is  not  perceived 
at  first,  in  consequence  of  its  insolubility.  It  crystallizes  in  deli- 
cate prismatic  needles,  or  in  white  translucent  tufts ;  and,  by 
uniting  with  acids,  forms  a  great  number  of  organic  salts. 

4.  quinina  [C^^^^N 0^=162)  is  also  foimd  in  connection 
with  Cinchonina  and  is  used  for  a  similar  purpose.  The  std- 
phjte  of  quinina  is  manufactured  on  a  large  scale,  and  sold  as 

Quinine.     It  is  intensely  bitter,  and  is  of  great  value  in  certain 
diseases. 


120  BIOLOGY  OF  PLANTS. 

5.  Strychmna  (C30H'6NO3=237.75)  is  found  in  the  nux  vom- 
ica [strychjios  mix  vomica),  the  St.  Ignatius  bean  {strychnos  igna- 
tia),  and  the  upas.  It  is  an  intensely  bitter  substance,  and  one 
of  the  most  violent  poisons  yet  discovered.  Its  action  is  ac^com- 
panied  with  symptoms  of  locked-jaw. 

6.  Emetia  or  Emdina  (C35H25NO9=308)  is  found  in  several 
plants,  especially  in  the  roots  of  the  ceph(Tlis  emetica,  ipecacuan- 
ha, and  possesses  most  powerful  emetic  properties.  It  gene- 
rally exists  in  the  form  of  a  yellowish  powder.  Six,  or  at 
most  twelve  grains,  occasion  violent  vonjiting,  followed  by  death. 

7.  JVicotina  is  the  peculiar  principle  of  tobacco,  a  most  viru- 
lent poison.  It  has  not  been  fully  analyzed,  but  is  supposed  to 
contain  more  nitrogen  than  any  of  the  other  alkaloids. 

8.  Conia  or  Conicina  (Ci~rP'*NO=108)  is  the  active  princi- 
ple of  conium  inaculatum  or  hemlock,  and  is  the  most  violent 
poison  known,  with  the  exception  of  hydrocyanic  or  prussic 
acid.  It  has  the  appearance  of  a  yellowish  liquid  oil,  with  a 
strong,  penetrating  smell,  and  acrid  and  corrosive  taste.  A  sin- 
gle drop,  put  into  the  eye  of  a  rabbit,  killed  it  in  nine  minutes. 
Three  drops,  used  in  the  same  way,  killed  a  strong  cat  in  a 
minute  and  a  half  It  is  a  common  opinion,  that  mineral  bod- 
ies are  the  most  poisonous,  but  it  is  not  the  case,  as  the  two 
most  violent  poisons  known,  are  derived  from  vegetables. 

9.  Solajiina,  (C^SH^'N^OS^  M.  Henry,)  is  found  in  the  ber- 
ries of  the  solanum  nigrum,  the  solanum  dulcamara,  or  common 
Nightshade,  and  in  potato-balls.  It  is  found  also  in  the  potato- 
root,  after  germination  commences,  and  in  the  epidermis.  It 
is  an  acrid,  narcotic  poison,  and  care  should  be  taken  not  to  use 
this  root,  after  germination  has  commenced. 

Parillina,  (C^H^O^)  is  found  in  the  smilax  sarsaparilla,  or  the 
common  sarsaparilla  of  the  shops,  a  substance  used  in  the  pre- 
paration of  mead,  beers,  etc.  It  diminishes  the  rapidity  of  the 
circulation,  and  acts  as  a  sudorific,  producing  perspiration,  and 
of  course  debilitates  the  system.  In  a  pure  state,  it  is  a  white 
powder,  with  a  sharp  and  bitter  taste,  slightly  astringent  and 
nauseous. 

Class  III.  Intermediate  Bodies.  In  this  class  are  included  seve- 
ral vegetable  principles,  which  have  not  yet  been  shown  to 
possess,  either  alkaline  or  acid  properties.  The  princij)al  of 
which,  are  coloring-matters,  fixed  and  volatile  oils,  resins  and 
gum-resins. 

1.  The  coloring-matters  of  vegetables,  are  usually  diflTused 
through  other  proximate  principles.     The   most  common  veg- 


COLORING  MATTERS.  121 

etable  colors,  are  green,  yelloWj  blue  and  red.  But  all  the  colors 
of  (lyed-stuffs,  are  produced  from  blue,  red,  yellow  and  black, 
though  the  latter  does  not  exist  in  the  vegetable  kingdom,  but 
is  formed  by  adding  mineral  bodies  to  the  acid  of  gall-nuts  or 
logwood. 

Btue  dyes  are  derived  from  the  indigo  plant  [indigofera),  a 
genus  of  plants  of  which  there  are  sixty  species.  They  are 
found  in  India,  Africa  and  America.  Litmus  has  a  blue  color, 
and  is  used  as  a  chemical  re-agent. 

Red  dyes  are  derived  from  the  cochineal,  an  insect  which  feeds 
on  one  species  of  the  cactus ;  from  lac,  archil,  madder.  Brazil- 
wood and  logwood. 

Lac  is  a  resinous  substance,  derived  from  the /cms  Indica  and 
religiosa,  and  is  commonly  known  as  shell-lac.  Archil,  is  obtain- 
ed from  a  species  of  lichen  {parmtlia  roccdla),  the  best  quality 
of  which  is  found  in  the  Canary  Islands. 

Madder  is  the  root  of  the  ruhia  tinctorum,  a  plant  cultivated  in 
countries  bordering  on  the  Mediterranean  Sea.  This  plant  is 
also  used  for  a  great  variety  of  colors,  forming  by  the  addition 
of  mineral  substances,  madder-yellow,  madder-orange  and  mad- 
der-brown . 

Brazil-wood  is  found  in  Brazil,  and  is  obtained  from  several 
species  of  the  ccEsalpina  (sapan,  crista,  etc.).  The  red  coloring 
matter  of  this  wood,  is  rendered  yellow  by  acids,  and  violet  by 
alkalies. 

Logwood  is  the  wood  of  the  Haematoxylon  Campeachianum 
found  in  Jamaica,  and  the  eastern  shores  of  Campeachy.  This 
wood  is  chiefly  employed  by  the  calico  printer,  to  give  cotton 
a  brown  or  black  color. 

Yelloio  dyes  are  obtained  from  the  quercitron  bark,  which  is 
taken  from  [quercus  nigra),  a  large  tree  growing  in  this  country  ; 
from  tumeric  [curcuma  longa),  saffron  [crocus  sativus),  and  from 
fustic  [morus  tinctoria),  a  large  tree  which  grows  in  Brazil ; 
from  iveld,  which  is  the  dried  leaves  of  reseda  luteola,  a  Eu- 
ropean plant ;  from  Persian  berries  [rhamnus  infectorius) ;  from 
sumac  [rhus  coriaria),  which  grows  spontaneously  in  Italy  and 
the  south  of  France. 

2.  Fixed  oils  are  usually  obtained  from  seeds,  as  the  almond, 
linseed  and  poppy-seed.  Olive-oil  is  extracted  from  the  pulp 
around  the  stone.  After  being  boiled,  these  oils  dry  more 
rapidly,  and  are  then  used  in  forming  paints ;  when  mixed 
with  lampblack,  they  constitute  Printer's  Ink.  In  drying  ra- 
pidly, these  oils  absorb  so  much  oxygen,  as  to  take  fire  spon- 


122  BIOLOGY  OF  PLANTS. 

taneously,  an  accident  which  frequently  occurs  when  cotton  or 
wool  in  large  quantities  is  moistened  with  them.  The  princi- 
pal fixed  oils,  are  olive,  croton,  palm,  cocoanut  and  linseed  oils. 

3.  Voldtile  oils  give  a  peculiar  flavor  to  plants,  called  aromatic. 
They  are  obtained  by  distillation  of  leaves,  or  by  expressing 
them  from  the  rinds  of  certain  fruits,  such  as  orange,  lemon,  hur- 
gamot,  etc.  Like  the  fixed  oils,  they  burn  with  a  clear,  white 
flame.  The  principal  volatile  oils,  are  oil  of  turpentine,  lemon, 
anise,  juniper,  camomile,  caraway,  lavender,  peppermint,  rose- 
mary, camphor,  cinnamon,  cloves,  sassafras,  mustard  and  bitter 
almonds. 

4.  Resins  are  the  juices  of  plants,  such  as  exude  from  pines 
and  balsams;  they  are  generally  solid,  brittle,  and  without  taste. 
The  resins  are  well  known,  under  the  names  of  rosin,  copal, 
shell-lac,  mastic,  dragon's  blood,  guaiacum,  etc.  The  uses  of 
these  are  well  known.     Copal  is  the  basis  of  all  varnishes. 

5.  Gum-resins  are  the  hardened  juices  of  several  species  of 
plants,  which,  when  cut,  give  out  a  milky  juice,  more  or  less 
thick ;  these  are  numerous,  and  many  of  them  are  valuable 
medicines.  Among  them  are  aloes,  asafcEtida,  ammoniac,  gal- 
banum,  gamboge,  myrrh,  olibanutn,  opium,  etc. 

Aloes  are  obtained  from  several  species  of  trees,  especially 
the  aloe  vulgaris,  from  the  leaves  of  which  it  exudes  when  cut 
It  is  of  a  reddish-brown  color,  and  of  an  intensely  bitter  taste. 

Ammoniac  is  obtained  from  the  dorema  ammoniacum,  and  is 
used  in  medicine,  but  is  the  least  powerful  of  all  the  fcetid  gums. 

Asafcetida  is  obtained  from  ferula  asafatida,  a  naiive  of  Per- 
sia ;  it  exudes  fi-om  the  roots  when  cut,  in  the  form  of  a  milky 
juice.  Its  taste  is  acrid  and  bitter ;  its  smell  strongly  alliaceous 
and  foetid.  It  is  employed  in  medicine,  especially  in  cases  of 
hysteria,  asthma  and  hooping-cough. 

Galhanum  is  obtained  from  the  plant  Galbanum  officinale,  a 
native  of  Persia  ;  its  taste  is  acrid  and  bitter,  and  its  smell  pe- 
culiar. It  is  used  in  njcdicine  for  similar  purposes  with  am- 
moniac, but  acts  widi  less  energy  than  asafcetida. 

Gamboge  is  obtained  from  a  tree  of  Siam,  and  also  of  Ceylon  ; 
but  the  s{)ecies  is  doubtful.  It  is  sold  in  commerce,  under 
three  forms,  pipe,  cake  and  lump  gamboge.  It  is  employed  in 
water-colored  painting,  forming  a  i)urc  and  fine  yellow.  It  is 
also  used  in  medicine  as  a  cathartic. 

Myrrh  is  obtained  from  the  balsamadendron  myrrha ;  a  tree 
which  grows  in  Arabia  and  Abyssinia.  It  exudes  from  the 
tree  in  the  state  of  a  yellowish-white  liquid,  which  soon  liar- 


NEUTRAL  SUBSTANCES.  123 

dens  into  a  brittle  solid,  of  a  transparent,  reddish-brown  color, 
and  of  a  bitter  and  aromatic  taste.  It  was  known  and  used  by 
the  ancients.  In  medicine,  it  is  considered  as  a  tonic.  The 
alcoholic  tincture  is  used  as  a  wash  for  the  teeth. 

Olihanum  is  the  frankincense  of  the  ancients.  According  to 
Lamark,  the  Arabian  variety  is  obtained  from  the  amysis  gilead- 
cn5i5,. while  Mr.  Colebrook  derives  the  Indian  olibanum  from  a 
large  tree  growing  on  the  mountains  of  India,  boswella  serrata. 
It  is  a  brittle,  white-yellow  substance,  of  an  acrid  and  aromatic 
taste,  and,  when  burnt,  diffuses  an  agreeable  odor,  on  which 
account  it  is  much  used  as  a  perfume. 

Opium  is  a  sedative  gum-resin,  which  exudes  from  the  heads 
of  the  papaver  somniferum,  or  poppy,  great  quantities  of  which 
are  used  in  medicine.  It  is  also  taken  in  large  quantities  as  a 
stimulant,  in  which  case  it  is  highly  poisonous. 

Class  IV.  Neutral  Substances  are  those  vegetable  principles 
which  possess,  neither  the  properties  of  acids  nor  bases,  and 
which,  so  far  as  is  known,  do  not  combine  in  definite  propodions* 
with  other  substances.  Under  this  class  are  arranged  a  very 
great  number  of  useful  substances.  Those  that  are  of  particu- 
lar interest  to  the  agriculturist,  may  be  included  under  the 
following  heads :  sugars,  amylaceous  substances,  gums,  gluteiwus 
svhstances,  caoutchouc,  extractive,  and  bitter  principles. 

I.  Sugar  (Ci2HioOio=]62)  is  a  term  applied  to  substances 
characterized  by  their  sweet  taste.  It  is  found  generally  in 
the  juices  of  plants,  from  which  it  is  extracted  by  boil- 
ing or  evaporation.  The  sap  of  common  sugar  is  obtained  from 
the  sugar-cane  (arundo  saccharifera),  the  sugar-maple  [acer  sac- 
charinum),  and  from  the  beet-root.  This  latter  source  of  sugar, 
was  introduced  into  France  by  Bonaparte,  during  the  war  be- 
tween France  and  England,  and  in  the  year  1 827,  the  quantity 
manufactured  was  2,650,000  lbs.  The  modes  of  making  sugar, 
derived  from  these  sources,  are  various,  and  can  only  be  alluded 

*  Most  bodies,  as  the  acids  and  alkalies,  combine  with  other  bodies 
in  definite  proportions  ;  that  is,  definite  quantities  of  one  body  combine 
with  definite  quantities  of  another  body,  to  form  a  third  body.  See 
Introduction.  But  there  are  also  a  large  class  of  bodies,  both  organic 
and  inorganic,  which  do  not  observe  this  law,  and  are  said  to  unite  in 
indefinite  proportions.  Water  and  sulphuric  acid,  for  example,  will 
unite  in  all  proportions.  Most  substances  which  are  held  in  solution 
in  water,  unite  with  it  in  indefinite  proportions,  up  to  the  point  of  satu- 
ration; such  as  salts,  sugars,  gums,  etc. 


124  BIOLOGY  OF  PLANTS. 

to  in  this  place.  When  the  sugar-cane  is  used,  the  green  canes 
are  ground  in  a  mill,  and  the  juice  evaporated  or  boiled. 

The  sugar-maple  is  tapped,  and  the  juice  received  in  buck- 
ets or  troughs,  and  then  boiled  until  the  water  is  all  evaporated. 
The  beet*  is  sliced  and  pressed  to  obtain  the  juice.  Many 
other  vegetables  contain  sugar,  as  the  sap  of  the  birch,  butter- 
nut, elm,  and  a  great  variety  of  trees ;  but  only  those  which 
have  been  mentioned  are  employed  for  this  purpose  to  any  con- 
siderable extent.     It  is  a  substance  of  universal  consumption. 

Liquid  sugar  is  distinguished  from  common  sugar,  by  the 
fact,  that  it  is  incapable  of  a-ijstalb'zation.  It  exists  in  various 
fruits  and  vegetable  juices.  It  constitutes  a  considerable  por- 
tion of  the  molasses  in  the  sugar  of  the  cane.  It  exists  also  in 
the  grape,  peach,  apple,  and  other  fruits.f 

Zea  Maiz,  or  Indian  corn,  also  contains  liquid  sugar.  Sugar 
of  grapes  is  not  so  white  as  connnon  sugar,  but  it  crystallizes 
much  more  readily. 

Manna  was  long  regarded  as  a  substance  which  fell  from  the 
heavens,  until  it  was  found  to  exude  from  several  trees,  of  which 
a  species  of  ash  [fraxinus  ornus),  found  in  Sicily,  is  the  most 
productive.  Manna  has  the  form  of  oblong  globules,  of  a  yel- 
lowish-white color,  and  is  used  in  medicine.  A  substance 
called  mannite,  or  mushroom  sugar,  is  similar  to  manna. 

Sugar  of  liquorice  is  obtained  from  a  plant  growing  in  Spain. 
The  root  is  the  common  liquorice-root,  and  the  black  balls,  sold 
under  the  name  of  liquorice-balls,  is  the  sugar. 

2.  Amylaceous  substances  include  common  starch,  hordein, 
lichnin,  inulin,  lignin,  diastase,  etc. 

Common  starch  is  secreted  in  most  of  the  grains,  the  potato, 
arrow-root,  tapioca,  sago,  and,  in  small  quantities,  in  nearly  all 
trees,  seeds  and  fruits.  When  wheat-flour  is  formed  into  paste, 
held  under  a  stream  of  water,  and  kneaded  until  the  water 
runs  off  clear,  a  tough  substance  remains  called  gluten,  while 
there  is  deposited  in  the  water  a  white  sediment,  which  is 
known  as  common  starch. 

Arrow-root  is  a  very  pure  starch,  extracted  from  the  root  of 
the  maranta  arundinacea,  a  plant  which  is  native  in  South 
America. 

Tapioca  is  also  a  very  pure  starch,  obtained  from  the  root  of 
a  South  American  i)lant,  iatropha  marihot.     The  roots  ai'c  sub- 


*  Thompson's  Organic  Bodies,  p.  G"-20.      Chaptal's  Ag.  Chemistry. 
Child's  Beet  Sugar.  t  Prout. 


NEUTRAL  SUBSTANCES.  125 

jeoted  to  pressure,  and  a  juice  extracted,  which  yields  it  in  the 
greatest  abundance.  It  is  a  fine  white  powder,  destitute  of 
taste  and  smell,  and  very  much  resembles  starch. 

Lignin  (Ci5H'OOio=180.)  This  name  is  given  to  the  fi- 
brous portions  of  wood,  which  remain  after  digesting  common 
wood  in  water,  muriatic  acid  and  alkalies.  It  constitutes  the 
skeleton  of  the  trunk  and  branches  of  trees.  The  quantity  of 
lignin  varies  in  different  kinds  of  wood,  but  generally  there  are 
96  parts  in  100.  Sulphuric  acid  converts  it  into  sugar,  and 
potash  into  ulmin.  It  is  the  substance  which  remains,  when 
wood  is  converted  into  charcoal,  or  rather  it  is  the  lignin  which 
is  converted  into  charcoal  by  heat.  It  may  be  made  into  ex- 
cellent bread.  The  inner  bark  of  flax  and  hemp,  and  the 
fibres  of  cotton,  are  probably  the  same  substance.  It  is  by  far 
the^  most  abundant  substance  in  vegetables. 

Fimgin  is  a  peculiar  vegetable  principle  derived  from  mush- 
rooms, and  approaches  in  its  chemical  character  closely  to 
woody  fibre. 

Diastase  is  a  substance  obtained  from  malted  barley,  and  ex- 
ists in  the  seeds,  and  also  in  oats  and  wheat.  It  has  the  pro- 
perty of  converting  starch  into  sugar,  and  is  used  in  the  pre- 
paration of  dextrine,  a  substance  employed  for  raising  bread.  It 
is  supposed  to  be  the  peculiar  principle  of  ferments,  and  hence 
its  great  use  in  culinary  operations. 

3.  Gums  are  the  exudations  of  several  trees,  such  as  the 
plum,  peach,  apple,  cherry,  etc.  but  the  principal  gums  are  gum 
arable,  from  the  acacia,  vera  and  arabica,  and  gum  Senegal,  from 
acacia  Senegal. 

Lintseed,  when  macerated  in  water,  is  converted  into  mucil- 
age, and  when  this  is  evaporated  to  dryness,  it  leaves  a  trans- 
lucent matter  behind,  similar  to  gum.  The  different  kinds  of 
gum  are  classed  by  Thompson  under  three  vegetable  principles, 
arabin,  bassorin  and  cerassin.  Gum  arable  is  principally  compo- 
sed of  arabin,  and  is  well  known  in  the  shops.  Gum  Senegal  is 
of  similar  composition.  Mucilage  of  lintseed  is  different  from 
the  preceding,  but  one  part  of  it  contains  arabin. 

Gum  Bassora,gum  iragacanth  and  gum  kuteera,  contain  bassorin^ 
and  are  articles  of  commerce.  These  gums  are  used  by  calico 
printers.  The  gum  from  the  cherry,  apricot,  plum,  peach  and 
almond  tree,  contain  cerasin,  which  is  the  cause  of  their  insolu- 
bility. Many  of  the  gums  are  easily  soluble,  and  are  used  for 
varnishes.  They  are  also  used  in  medicine  to  a  considerable 
extent. 

II 


126  BIOLOGY  OF  PLANTS. 

Calendulin  is  a  peculiar  principle  found  in  the  marigold ;  it 
is  a  yellowish,  translucent,  brittle  substance. 

Saponin  is  another  peculiar  principle,  found  in  a  root  which 
grows  in  Greece  and  eastern  countries ;  it  may  be  used  for 
soap. 

4.  Glutinous  substances.  When  wheat-flour  is  kneaded  into 
paste  with  a  little  water,  it  forms  an  elastic,  soft  and  ductile 
mass.  When  this  is  washed  under  a  stream  of  water  until  it 
runs  off  colorless,  there  remains  a  tough,  elastic  substance,  of  a 
gray  color,  called  gluten.  It  was  discovered  in  1742,  by  Bec- 
caria,  an  Italian  philosopher.  It  has  scarcely  any  taste,  and 
adheres  tenaciously  to  most  bodies  with  which  it  is  brought  in 
contact.  It  is  the  substance  which  renders  bread  tough,  and 
enables  the  dough  to  rise  by  ferments.  It  exists  in  all  kinds  of 
grain,  and  their  value  depends  upon  its  quantity.  Modern 
chemists  hiive  resolved  it  into  four  distinct  principles,  albumen, 
emulsin,  mucin  and  glutin. 

Vegetable  albumen  is  obtained  by  digesting  the  gluten  of  wheat 
in  alcohol,  until  everything  soluble  is  taken  up.  It  is  a  bulky 
substance  of  a  greyish  color,  soluble  in  water,  and  is  the  sub- 
stance in  the  seed,  which  takes  an  important  part  in  germina- 
tion. 

Emulsin  (C'^^H^SN^O^)  is  found  principally  in  almonds,  and 
resembles  starch,  when  dissolved  in  water.  It  has  the  pecu- 
liar property  of  decomposing  amygdalin,  and  of  forming  hydro- 
cyanic acid,  and  the  volatile  oil  of  bitter  almonds. 

Mucin  is  taken  up  by  hot  alcohol,  when  the  gluten  of  wheat 
is  put  into  it.  It  burns  like  animal  matter,  and  is  more  soluble 
than  gluten. 

Glutin  (C^J^H'^'NiO^)  is  also  taken  up  by  boiling  alcohol  with 
the  gluten  of  wheat,  and  is  obtained  after  precipitating  all  the 
mucin.  It  is  a  yellow,  translucent  substance,  almost  insoluble 
in  water,  and  generally  exists  in  wheat  in  connection  with 
starch. 

Zein  is  a  name  given  to  the  gluten  of  zea  mais,  or  Indian 
corn.  It  differs  from  the  gluten  of  wheat  by  containing  less 
nitrogen. 

Viscin  (C^^WK)'^)  is  a  soft  elastic  substance,  of  a  brown 
color,  identical  with  bird-lime.  It  adheres  firmly  to  the  fingers 
like  glue,  and  exists  in  several  species  oi' acacia. 

Pollenin  (C'^H^OOI^)  is  derived  from  the  pollen  of  the  pinus, 
abies  and  sylvtstris,  and  is  sui)j)osed  to  characterize  every  spe- 
cies of  pollen. 


NEUTRAL  SUBSTANCES.  127 

Lea-umin  is  a  vegetable  principle,  found  in  the  fleshy  cotyle- 
dons of  all  papilionaceous  plants,  such  as  peas,  beans,  etc.  and 
seems  to  be  intermediate  between  gluten  and  vegetable  albu- 
men.* 

Amygdalin  (C^^^H^CN^O^S)  is  found  in  bitter  almonds. 

5.  Caoutchouc  is  obtained  from  the  milky  juice  of  several 
species  of  trees  in  South  America,  and  in  the  East  Indies.  It 
is  is  well  known  as  India-rubber. 

6.  Extractive,  The  term  extractive  is  now  restricted  to  what 
is  obtained  by  macerating  vegetables  in  water,  and  evaporating 
the  infusion  to  dryness.  There  is  a  great  variety  of  these  ex- 
tracts, and  they  are  used  extensively  in  medicine,  in  which  case 
they  are  generally  preserved  in  alcohol. 

7.  Bitter  Principle.  Many  vegetable  substances  have  an  ex- 
tremely bitter  taste,  and,  on  that  account,  are  employed  in  medi- 
cine. This  is  the  case  with  the  roots  of  the  quassia  gentian, 
hop,  camomile,  worm-wood,  etc. 

The  following  are  some  of  the  most  remarkable  bitter  sub- 
stances which  have  been  examined. 

Quassite,  obtained  from  the  quassia  amara  and  excelsa.  Gen- 
tianUe,  from  the  seeds  of  the  gentiana  lutea.  Cytisite,  from  the 
seeds  of  the  cytisus  laburnum.  Bryonite,  from  the  root  of  the 
Bryonia  alba,  or  white  bryony.  Centaurite,  from  the  leaves  of  the 
centaurea  benedida,  or  blessed  thistle,  ^^thanitite,  from  the  cydor- 
tnen  Europeum,  or  sow-wort.  Bitter  principle  of  wormwood,  trora 
the  artemisia  absynthium,  or  worm-wood.  Colocynthite,  from  the 
cucumii  colocynthii,  or  colocynth  of  pothecaries.  Bitter  principle 
of  aloes.  Xanthropicrite.  Berbente,  from  the  bark  of  the  com- 
mon barberry,  berbtris  vulgaris.  Lupinite,  from  the  seeds  of  the 
lupinus  albus.  Phloridzite,  from  the  bark  of  the  apple,  pear, 
cherry  and  plum  tree. 

It  would  be  nearly  useless  to  enumerate  any  more  substan- 
ces, as  the  peculiar  products  of  vitality,  for  but  little  more  can 
be  done  in  this  work,  than  to  mention  their  names.  These  are 
mostly  technical  and  unintelligible  to  the  farmer.  Perhaps  too 
many  have  already  been  inserted.  The  object  is  simply  to  give 
the  reader,  some  idea  of  the  great  number  of  compounds,  which 

*  There  are  found  in  animal  bodies  three  substances,  which  appear 
to  be  identical  with  gluten,  vegetable  albumen  and  legumin ;  they 
are  casien,  the  curd  of  cheese  ;  albumen,  or  the  white  of  eggs ;  and 
fbrin,  the  substance  which  constitutes  the  muscular  fibre  of  animals 
It  is  probable,  that  these  substances  are  derived  by  animals  from  vege- 
tables. They  contain  large  quantities  of  nitrogen,  and  hence  th«ir 
use  for  manure- 


128  BIOLOGY  OF  PLANTS. 

have  been  found  in  the  vegetable  kingdom,  and  which  cannot, 
with  but  few  exceptions,  be  formed  h}^  any  known  chemical 
agents.  This  enumeration  will  perhaps  lead  some  scientific 
farmers  to  examine  more  fully  the  vegetable  principles,  and  to 
study  in  works  where  they  are  found  fully  described,  their  cha- 
racters and  uses. 

It  jnay,  however,  be  useful,  and  much  more  intelligible  to  the 
common  reader,  to  describe  the  sources  of  several  articles  of 
food  and  of  medicine,  as  they  exist  in  the  roots,  wood,  bulbs, 
leaves,  fruit,  or  seeds  of  plants. 

I.  Roots.  The  principal  roots,  employed  in  medicine  and 
the  arts,  are  the  following. 

1.  Beet-root  {beta  vulgai'is).  There  are  two  varieties,  the  red 
and  the  white  beet.  This  is  a  well  known  vegetable.  It  con- 
tains from  5  to  10  per  cent,  of  sugar,  generally  from  8  to  9  per 
cent. ;  hence  its  use  for  this  purpose. 

2.  Cairot  [dauciis  carota).  This  is  also  a  well  known  root.  It 
is  used  for  fattening  cattle,  and  is  preferable  to  the  beet  for  that 
purpose.  It  contains  sugar,  and  a  peculiar  principle,  called 
caratin. 

3.  Rhuharh  [rheum  plamatum,  ausfrale,  undulatum,  etc.)  Three 
varieties  of  rhubarb  are  known  in  commerce,  Russian,  Turkey, 
East  India  or  Chinese  rhubarb.  It  is  a  yellow  root  possessing 
powerful  purgative  properties,  for  which  it  is  used  in  medicine. 

4.  Rattle-snake  root  {polygala  senega),  is  a  native  of  Virginia, 
and  is  employed  by  the  Indians  as  a  cure  for  the  bite  of  the 
rattle-snake.  The  peculiar  vegetable  principle  upon  which  this 
effect  depends,  is  called  senegin. 

5.  Jalap  [Jpomea  jalappa),  is  a  well  known  active  cathartic.  It 
is  a  native  of  Mexico,  but  the  best  jalap  comes  from  Vera  Cruz 
and  South  America.  The  active  properties  are  supposed  to  be 
due  to  the  resin  which  it  contains. 

6.  Gentian  [gentiana  lutea),  grows  in  the  mountains  of  Swit- 
zerland and  America,  and  is  a  bitter  root,  yielding  to  water  an 
extract,  which  produces  intoxicating  effects. 

7.  Valerian  {Valeriana  ojficinalis),  is  a  root  much  used  as  an 
anti-spasmodic  in  epilepsy,  etc. 

8.  Horse-radish  {cochlearea  aimorica),  is  a  root  of  an  acrid 
taste,  which  is  due  to  a  small  quantity  of  volatile  oil. 

9.  Siveet-Jlag  {acorus  calamus),  contains  a  volatile  oil,  inuline, 
gum-extractive,  resin,  with  phosphate  and  muriate  of  potash. 


NEUTRAL  SUBSTANCES.  129 

10.  Ipecacuana  {callicocca  ipecmuand),  common  ipecac,  is  the 
root  of  a  plant  which  grows  in  Brazil.  The  root  is  about  the 
thickness  of  a  qnill,  and  varies  considerably  in  color.  When 
pounded,  it  forms  the  mildest  and  safest  emetic. 

11.  Sarsaparilla  {smilax  sarsaparilla),  is  a  native  of  South  x\mer- 
ica,  and  is  used  in  medicine  in  certain  chronic  diseases,  and  in 
syphilis. 

12.  Ginger  [amomum  zingiber),  is  a  plant  found  in  India,  and 
well  known  to  the  ancients.  It  is  a  whitish  root,  but  when 
powdered  as  in  common  ginger,  it  is  yellowish.  This  root 
makes  a  very  delicate  preserve. 

13.  Pomegranate  tree  [punica  granatum),has  been  employed  in 
medicine.  It  contains  a  substance  similar  to  mannite,  which 
has  been  called  grenadia. 

14.  Crameria  ratanhia  is  a  root  found  in  South  America,  and 
yields  a  powerful  and  safe  astringent  matter,  used  in  njedicine. 
The  active  principle  exists  in  the  bark  of  the  root. 

II.  Bulbs  are  the  tubercles  connected  with  the  roots  of 
vegetables,  analogous  to  buds.  The  following  are  the  prin- 
cipal bulbs  or  tubers,;  which  are  used  for  food,  in  medi- 
cine, and  the  arts. 

1.  Potato.  This  is  the  bulb  of  the  solanum  tvherosum,  which 
is  found  wild  in  the  mountains  of  Chili.  They  contain  but 
little  nitrogen.  They  also  contain  the  poisonous  alkali,  so- 
lenin,  which  exists  in  the  epidermis  when  they  begin  to  germi- 
nate. They  are  generally  composed  in  one  hundred  parts,  of 
eight  parts  of  fibrin,  ten  of  starch,  one  of  gum,  acids  and  salts, 
and  eighty-one  of  water.     Their  uses  as  food  are  well  known. 

2.  Jerusalem  artichoke  is  a  bulbous  root  of  the  hdianthus  tube- 
rosus,  a  South  American  plant.  It  is  very  productive,  of  a 
sweetish  taste,  very  watery,  and  very  valuable,  as  they  will  grow 
on  a  light  soil,  and  yield  abundantly  without  much  cultivation. 
One  acre  sometimes  yields  sixty  or  seventy  tons.  It  is  singular, 
that  this  valuable  root  is  not  more  cultivated. 

3.  Garlic  is  the  bulbous  part  of  the  root  of  the  allium  sativum. 
It  is  found  in  Sicily,  is  remarkable  for  its  strong  smell  and  taste, 
and  was  celebrated  by  the  ancients,  both  as  an  article  of  food, 
and  as  a  medicine. 

4.  Onion  is  the  root  of  the  allium  cepa^  a  well  known  vegeta- 
ble, used  as  food. 

5.  Squill  is  the  bulb  of  the  scUla  nmritima  a  native  of  Spain, 

11* 


130  BIOLOGY  OF  PLANTS. 

Sicily  and  Syria.  Its  bulb  is  nearly  the  size  of  a  human  head, 
is  shaped  like  a  pear,  and  formed  of  fleshy  scales.  It  has  no 
smell,  but  its  taste  is  bitter,  nauseous  and  acrid.  It  is  used  in 
medicine  to  excite  nausea  and  vomiting. 

6.  Saffron  {colchicum  autumnale)  is  used  in  medicine  for  the 
gout.  The  tube  is  egg-shaped,  and  covered  with  a  brown 
membranous  coat.  The  recent  bulbs  have  no  smell,  but  are 
bitter,  hot  and  acrid  to  the  taste.     It  is  poisonous. 

III.  Woods.  The  wood  of  different  trees  differs  but  little 
in  composition;  generally  about  forty-eight  or  forty-nine  parts 
of  carbon,  six  of  hydrogen,  and  forty-four  or  forty-five  of  oxy- 
gen, are  found  in  one  hundred. 

The  vegetable  fibres  in  herbaceous  plants  are  similar  to  the 
wood  of  trees.  Of  these,  hemp,  flax  and  cotton  are  the  most 
important,  because  of  their  use  in  the  arts.  These  sub- 
stances, however,  might,  with  equal  propriety,  be  regarded  as 
the  inner  bark. 

Fldx.  The  fibres  of  flax  are  "  transparent,  cylindrical  tubes, 
articulated  and  pointed  like  a  cane."  It  was  known  to  the  an- 
cients, and  has  been  an  article  of  universal  consumption. 

Hemp  is  precisely  similar  in  composition  with  flax,  but  has 
a  coarser  fibre. 

Cotton  is  the  soft  down  which  envelopes  the  seeds  of  differ- 
ent species  of  gossypium,  from  which  plant  the  cotton  of  com- 
merce is  procured.  "  The  fibres  of  cotton  are  transparent,  glas- 
sy tubes,  flattened  and  twisted  around  their  own  axis."  By 
this  test  the^ne  linen  of  Egypt  is  found  to  be  linen,  and  not  cot- 
ton, as  some  interpreters  of  tlie  Bible  have  supposed. 

"  Paper  is  prepared  from  hemp,  cotton  and  linen  rags.  These 
rags  are  bleached  and  reduced  to  an  impalpable  pulp."  This 
pulp  is  spread  equally  on  a  wire  sieve,  and  the  paper  placed 
upon  cloths  to  dry ;  after  which  it  is  sized  and  pressed. 

IV.  Leaves.  The  leaves  of  plants  much  resemble  each 
other  in  appearance,  but  contain  various  vegetable  principles. 

1.  Senna  is  the  leaf  of  the  cassia  acuiifolia  and  ohovata,  na- 
tives of  upper  Egypt  and  Nubia.     It  is  a  valuable  cathartic. 

2.  Belladonna  is  tlie  dried  leaves  of  the  atropa  belladonna,  or 
deadly  night  shade.     It  is  poisonous,  but  used  in  medicine. 


SEEDS  AND  PLANTS.  131 

3.  Tobacco  is  formed  from  the  leaf  of  the  nicoliaiia  tahacum,  a 
native  of  Tabaco  in  Mexico,  from  which  it  receives  its  name. 
It  is  a  well  known,  and  much  used  narcotic  poison.  It  con- 
tains at  least  eighteen  different  substances.  IsTicotina  is  the 
cause  of  its  poisonous  effects. 

4.  Fox-glove,  the  digitalis  purpurea,  is  a  well  known  vege- 
table, the  leaves  of  which  were  introduced  into  medicine  by 
Dr.  Withering. 

5.  Tea  is  composed  of  the  dried  leaves  of  the  thea  bohea,  and 
thea  viridis,  natives  of  China  and  Japan.  The  different  varieties 
of  tea,  are  all  derived  from  these  two  species.  The  leaves  of 
this  plant  are  not  fit  for  use,  until  the  shrub  has  vegetated  three 
years.  The  leaves  are  collected  and  exposed  to  the  steam  of 
boiling  water,  and  every  leaf  is  then  rolled  up  with  the  hand, 
put  upon  plates  of  copper,  and  held  over  the  fire,  until  they  are 
shrivelled.  To  this  heating  process  tea  owes  its  peculiar  flavor. 
Its  uses  are  well  known.  It  is  a  powerful  stimulant,  acting  up- 
on the  nervous  system,  and  producing  an  exhilarating  effect. 

6.  James'  tea  is  the  leaf  of  the  ledum  latifolium,  a  native  of  this 
country. 

7.  Paraguay  tea  is  the  leaf  of  a  native  plant  of  South  Amer- 
ica, of  the  holly  genera,  and  is  used  as  a  tea.  It  is  a  stimulant, 
and,  if  used  in  excess,  occasions  intoxication  and  delirium,  tre- 
mens. 

8.  Isatis  tinctoria,  or  woad,  is  the  plant  from  which  indigo  is 
olbtained. 

9.  Asparagus  officinalis  is  a  valliable  vegetable,  the  young 
shoots  of  which  are  used  for  food. 

V.  Seeds  and  fruits  constitute  the  most  important  articles 
of  food.  They  contain  all  the  elements  necessary  for  the  sup- 
port of  animals. 

1.  Wheat  is  the  seed  of  the  triticum  hybernum,  winter  wheat, 
and  T.  aestivum,  or  summer  wheat,  the  most  important  of  all  the 
smaller  grains.  Two  or  three  other  species  have  been  cultiva- 
ted. Its  properties  and  uses  are  well  known.  A  sample  of 
French  wheat,  analyzed  by  Vauquelin,  yielded  seventy-one  parts 
of  starch,  ten  of  gluten,  five  of  sugar,  three  of  gum,  and  ten  of 
water  in  one  hundred. 

2.  Rye  is  the  grain  of  the  secale  cereale.  It  is  subject  to  the 
disease  called  ergot,  which  is  a  species  of  fungus  plants,  of  a 
long,  black  appearance,  blunt  angles,  and  about  one  inch  in 


132  BIOLOGY  OF  PLANTS. 

length.  By  some  the  ergot  is  regarded  as  the  effect  of  an  in- 
sect. This  substance  is  a  violent  poison.  Rye  is  similar  to 
wheat  in  composition,  but  contains  less  starch  and  gluten. 

3.  Oats  are  the  seeds  of  the  avena  saliva,  and  are  a  valuable 
fodder  for  horses.  In  some  countries,  as  Ireland,  tiie  oat  is  em- 
ployed for  bread. 

4.  Barley  is  the  seed  of  the  hordeum  vulgare,  and  is  used  for 
brea<l,  malt  liquors,  and  for  obtaining  ardent  spirits. 

5.  Rice  is  the  seed  of  the  orysa  saliva,  a  well  known  article 
of  food,  especially  in  warm  countries. 

6.  Maize  or  Indian  corn.  The  zea  maize  is  a  native  of  this 
country,  but  is  now  cultivated  in  Europe,  and  is  one  of  the  most 
valued  of  our  grains.  It  is  coniposed  of  starch  eighty-four,  zein 
three,  albumen  three,  gum  two,  sugar  two,  water  six,  in  one 
hundred. 

7.  Peas  are  the  seeds  of  the  pisum  sativum,  and  constitute  a 
very  nutricious  article  of  food. 

8.  The  small  bean  [viciafaba),  is  used  as  an  article  of  food,  and 
also, 

9.  The  kidney  bean,  {phaseolus  vulgaris).  They  contain  a  large 
quantity  of  animo-vegetable  matter. 

10.  Lentiles  [ei-vum  lens),  contain  a  larger  quantity  of  animo- 
vegetable  matter  than  the  kidney  bean. 

11.  Orange  {citrus  aura.nlium),  and  {cilrus  medica),  are  well 
known  fruits  which  are  employed  both  in  medicine  and  for  food. 

12.  Cherry  {prunus  cerassus),  are  a  cultivated  fruit,  of  which 
there  are  several  varieties. 

13.  Almond,  Peach  and  Apricot  are  quite  different  fruits,  but 
the  trees  are  botanically  identical  {amygdalus  communis). 

14.  Pear  [pyrus  communis),  apple  {pyrus  malus),  are  too  well 
known  to  need  description. 

15.  Gooseberry  [ribes  grossularia),  Black  currant  (jR.  nigrum). 
Red  currant  {R.  riibrum),  are  valuable  acid  berries. 

16.  Grapes  are  the  fruit  of  tlie  vilis  vinifera,  and  are  exten- 
sively cultivated  in  France  and  the  soutli  of  Europe,  both  for 
the  wine  vv'hich  their  juice  yields,  and  for  raisins. 

17.  Mango  is  the  fruit  of  the  mangifera  indica  or  domcstica^  a 
native  of  Lidia.  The  fruit  varies  from  the  size  of  an  apricot,  to 
that  of  a  pear.  Its  skin  is  soft  and  smooth,  the  fleshy  part  of 
the  fruit  is  juicy,  and  has  a  very  sweet  and  acidulous  taste.  It 
contains  a  great  quantity  of  crystallizablc  sugar,  citric  acid  and 
gum. 

18.  Pepper  is  the  berry  of  the  piper  nigrum.     Tiie  unripe 


SEEDS  AND  FRUITS. 


133 


berries  are  hlack  pepper,  and  the  ripe  berries  deprived  of  their 
outer  skins  constitute  white  pepper.  Oerstedt  detected  a  matter 
in  tliis  seed,  which  Jie  called  piperin,  a  peculiar  vegetable  prin- 
ciple. It  is  composed  of  piperin  C^"H'2"2O^N=340.  An  acid, 
fatty  matter,  a  volatile  oil,  extractive,  gum,  starch,  bassorin  in 
abundance,  a  malate,  and  some  other  salts. 

J9.  Cubebs  are  the  berries  of  the  piper  cubeba,  and  are  simi- 
lar in  appearance  to  pepper-corns.  They  are  of  an  aromatic 
and  acrid  taste,  and  contain  a  peculiar  vegetable  principle 
called  cubebin. 

20.  Cayenne  pepper  is  the  fruit  of  the  capsicum  annuum,  a  na- 
tive of  India,  but  cultivated  in  the  West  Indies.  The  following 
is  the  analysis  of  Braconnot :   100  parts  contain  of 


Starch  9. 

A  very  acrid  oil  1.9 

Wax,  with  red  coloring-matter  0.9 
Gum  of  a  peculiar  nature 


Animalized  matter  5.0 

Citrate  of  potash  6.0 

Lignin  67.8 

6.0      Muriate  &  phosphate  of  potash  3.4 

100.0 


The  acrid  oil  gives  it  its  peculiar  bitter  and  burning  taste.  It  has 
been  called  capsicin.  Cayenne  is  a  well-known  spice,  and  is 
much  used  in  the  preparation  of  Thompsonian  nostrums. 

21.  Jamaica  pepper  (pimento),  the  fruit  of  the  rmpius  pimento, 
resembles  bladk  pepper,  and  is  prepared  in  the  same  w^ay  from 
the  unripe  berries.  Their  odor  and  taste  resemble  a  mixture  of 
pepper,  cinnamon  and  cloves.  The  following  is  the  analysis  of 
Bonastre,  of  100  parts. 

3.2 
8.0 
1.6 

16. 

1.9 
3. 


Volatile  oil 

5. 

Resinous  matter 

Soft  green  resin 

2.5 

Extract  containing  sugar 

Solid  fat  oil 

1.2 

Malic  and  gallic  acids 

Extract  containing  tannin 

39.8 

Lignin 

Gum 

7.2 

Ashes  containing  salts 

Brown  coloring-matter 

8.8 

Moisture 

98.2 


22.  TVxmanncfe' consist  of  the  pulpy  matter  which  fills  the 
pods  of  the  tamarindus  Indica.  It  is  a  well  known  sweet-meat, 
brought  to  this  country  preserved  in  sugar.  It  consists,  ac- 
cording to  the  analysis  of  Vauquelin,  of 


Supertartrate  of  potash 

300 

Tartaric  acid 

144 

Gum 

432 

Malic  acid 

40 

Sugar 

1152 

Feculent  matter 

2880 

Jelly 

576 

Water 

3364 

Citric  acid 

864 

9752 

134 


BIOLOGY  OF  PLANTS. 


23.  Juniper  henries  grow  on  a  small  shrub  {juniperus  commurtis) 
in  Scotland.  They  contain  a  peculiar  volatile  oil,  which  im- 
parts its  peculiar  flavor  to  Dutch  gin,  in  the  manufacture  of 
which  they  are  highly  valued. 

24.  Anise  is  the  seed  of  a  plant  [pimpinella  anisum)  cultivated 
in  Spain  and  Malta.  The  seeds  have  a  peculiar  aromatic  smell, 
a  pleasant  sweetish  taste,  and  are  used  in  medicine, 

25.  Mustard.  There  are  two  species  of  this  plant  found  in  this 
country  ;  the  sinapis  nigra  or  black  mustard,  and  the  sinapis  al- 
ba or  white  mustard.  The  composition  of  both  is  similar. 
They  contain  a  peculiar  principle,  called  sinapin  (C^'^H^SQ^  and 
2  equivalents  of  sulphur =268).  The  white  mustard,  according 
to  John,  is  composed  as  follows :  of  an  acrid,  volatile  and  a 
yellow  fixed  oil,  brown  resin,  gum,  lignin,  albumen,  phospho- 
ric acid  and  salts.  Mustard  acts  as  a  powerful  excitant.  Its 
uses  are  well  known.  White  mustard  has  been  a  celebrated 
remedy  for  dispepsy. 

26.  Cocoa-nut.  This  is  the  fruit  of  a  species  of  palm  [cocos 
nucifera).  The  kernel  contains  a  quantity  of  fixed  oil,  which  is 
used  m  India  for  lamps.  The  fibres  of  the  outer  coat  are 
formed  into  excellent  cordage.  It  contains  within,  a  milky, 
sweetish,  saline  fluid. 

27.  Cucumber.  The  common  cucumber  {cucumis  sativus)  is 
composed  of  the  following  substances. 


Water  97.13 

Substances  similar  to  fungin  0-53 
Soluble  vegetable  albumen  0.13 
Resin  0.04 

Extractive  vi^ith  sugar  1.66 


Phosphate  of  lime  and  of  pot- 
ash, phosphoric  acid,  am- 
moniacal  salt,amalate,  sul- 
phate and  muriate  of  pot- 
ash, and  phosphate  of  iron  0.5 
lUO.OO 


28.  Thorn-apple  [datura  stramonium)  is  too  well  known  to 
need  description.  It  has  narcotic  properties,  similar  to  bella- 
donna. 

29.  JVuimeg  is  the  fruit  of  the  myristica  moschata,  and  is  much 
used  as  an  article  for  seasoning  food.  It  is  a  native  of  the  Mol- 
lucca  Islands.  The  covering  of  the  nut  is  called  mace.  It  has 
been  analyzed  by  M.  Bonastre,  and  consists,  in  100  parts,  of 

0.8 
56. 
5. 

TooT 


Fat  butyraccous  oil 

31.6 

Acid 

Volatile  oil 

6.0 

Lignin 

Starch 

2.4 

Loss 

Gum 

1.2 

DEFINITIONS  AND  DESCRIPTIONS.  135 

30.  Coffee  bean  is  the  fruit  of  the  coffcea  Arahica,  and  is  in 
general  use  for  the  manufacture  of  coffee.  The  tree  is  a  native 
of  Arahia,  but  is  extensively  cultivated,  both  in  the  East  and 
West  Indies.  It  contains  a  peculiar  principle  called  caffein 
(C4H2NO=48.5).  According  to  the  analysis  of  Hermann,  the 
coffee  bean,  from  Martinique,  contains 

Resin  68.       I  Lignin  11386 

Extractive  310.  Loss  12 


Gum  144. 


1920 


31.  Hops  ave  obtained  from  the  humulus  lupilus,  and  are  em- 
ployed extensively  in  the  manufacture  of  beer  and  ale.  The 
hop  is  a  dioecious  plant,  the  female  alone  bearing  fruit.  It  is 
a  valuable  plant,  and  was  introduced  into  England  in  the  reign 
of  Henry  the  VIII. 

32.  Dates  are  the  fruit  of  the  palm,  [pTicznix  datilyfera^)  and 
constitutes  an  important  article  of  food  in  several  warm  coun- 
tries. It  has  a  sweet  taste,  and  contains  a  large  quantity  of 
sugar. 

This  catalogue  of  fruits  and  seeds,  and  other  products  of  the 
vital  principle,  might  be  increased  ;  but  a  sufficient  number 
liave  been  noticed  here  to  give  the  reader  some  idea  of  their 
number,  variety,  properties  and  uses.  They  are  intended  chief- 
ly, as  a  convenient  reference  to  those  who  may  not  have  access 
to  better  sources  of  information. 

There  are  several  other  simple  bodies  contained  in  vegetables 
besides  oxygen,  hydrogen,  carbon  and  nitrogen  ;  but  as  they  do 
not,  by  their  combinations,  form  the  peculiar  products  of  the 
vital  principle,  they  are  not  noticed  in  this  place.  They  will 
more  properly  come  under  review  in  the  next  two  sections,  which 
treat  of  the  source  and  assimilation  of  the  simple  substances 
which  enter  into  the  composition  of  plants.  It  should  also  be 
remarked,  that  those  substances  which  nourish  vegetables,  are 
often  derived  from  organic  bodies,  and  that  many  compounds 
are  classed  a$  organic,  simply  because  they  are  derived  from 
organic  bodies.  But  they  are  the  products  of  death  or  decay^ 
not  of  life. 

Sect.    2.     Dejinitions  and  Descriptions. — Source  and  as- 
similation of  the  Organic  Constituents  of  Plants. 

1.  Humin  is  a  substance  found  in  the  soil.  It  is  composed 
of  carbon,  hydrogen  and  oxygen,  and  is  similar  to  woody  fibre. 


136  BIOLOGY  OF  PLANTS. 

In  fact  it  is  wood  partially  decayed.     It  is  insoluble  in  water, 
but  is  converted  by  the  agency  of  water,  air  or  alkalies,  into 

2.  Humic  acid,  which  is  identical  in  composition  with  it.  Hu- 
mic  acid  is  a  brownish-black  substance,  floculent  when  first  pre- 
cipitated, and  soluble  in  2,500  times  its  weight  of  water,  and 
becomes  less  and  less  soluble  the  longer  it  is  exposed  to  the 
air.  It  is  composed,  according  to  Sprengel,  of  carbon  58. ,  hy- 
drogen 2.10,  and  oxygen  39.90  in  100  parts.  Boullay  gives  the 
composition  of  g-e?c  acii/,  which  is  identical  with  humic  acid. 
Malagutti  gives  nearly  the  same  composition. 

Boullay.  Malagiitti 


Oxygen  55.70  or  15  atoms 

Hydrogen  4.81       15 

Carbon  38.49      30 


Oxygen  57.48 

Hydrogen  3.76 

Carbon  37.36 

yy.60 


Hence  its  composition  may  be  represented  by  C^^VL^^O^^==oy 
about  58  per  cent,  of  humic  acid  is  carbon. 

3.  Crenic  acid,  from  krene  the  Greek  word  for  fountain,  is 
composed,  according  to  the  analysis  of  Hermann,  of  C^'H^^NO^. 
When  pure  it  is  of  a  yellow  color,  quite  transparent,  with  no 
tendency  to  crystallize.  It  has  no  odor,  but  its  taste  is  sharp,  at 
first  acid,  and  afterwards  astringent.  When  in  solution  the 
astringent  taste  alone  can  be  perceived.  It  is  excessively  soluble 
in  loater  and  alcohol.  It  combines  with  lime,  and  forms  the  cre- 
naie  of  lime,  which  is  soluble  in  water,  and  the  subcrenate  of 
lime  which  is  insoluble.  The  crenates  of  potassa,  ammonia  and 
soda,  resemble  extracts  of  a  yellowish  color,  very  soluble  in 
water,  and  in  weak  alcohol. 

The  crenate  of  magnesia  is  readily  dissolved  in  water,  but  the 
neutral  crenate  of  alumina  is  insoluble,  while  the  subsalt  is  solu- 
ble. The  crenate  of  iron  is  also  soluble  in  water.  Hence,  as  all 
these  substances  are  found  in  the  soil,  and  nearly  all  are  solu- 
ble in  water,  they  nuist  enter  the  organs  of  plants  with  that  fluid. 

4.  Jijjocrenic  acid  is  formed  from  the  crenic,  by  simply  ex- 
posing the  latter  to  the  air.  Its  composition  niay  be  represent- 
ed thus:  C^^H^'^N^O^.  It  is  a  brown  extract,  possessing  a 
purely  astringent  taste.  It  is  slightly  soluble  in  water,  is  readilj'^ 
dissolved  in  crenic  acid,  and  slowly  in  alcohol.  As  the  crenic 
acid  always,  upon  exposure,  changes  into  this  acid,  the  existence 
of  the  former  appears  essential  to  the  i)roduction  of  the  latter. 

The  ffy?ocrena/e.s  of  potassa,  ammonia  and  soda  arc  black,  fria- 
ble masses,  and  when  soluble  in  water,  are  of  a   dark-brown 


DEFINITIONS  AND  DESCRIPTIONS.  137 

color.     Those  of  lime,  magnesia,  etc.  are  of  a  yellow  color,  and 
soluble  in  water ;  but  the  subsalts  are  insoluble. 

5.  ^pocrenate  of  alumina,  when  neutral,  is  insoluble ;  but 
soluble  when  there  is  an  excess  of  acid.  Jlpocrenate  of  the  pro- 
toxide of  iron  is  soluble,  but  the  salt  of  the  peroxide  is  insoluble 
in  water;  hence  this  acid  with  its  various  salts  are  generally 
soluble  in  water  to  some  extent,  and  must  be  conveyed  into  the 
organs  of  plants. 

6.  Extract  of  humus  and  glarin  are  brown  matters  composed 
mostly  of  carbon,  hydrogen  and  oxygen.  The  above  substances 
form  the  chief  ingredients  of  vegetable  vwuld,  and  pass  into 
each  other  in  the  changes  which  take  place  in  the  soil. 

When  plants  are  subjected  to  ultimate  analysis,  that  is,  re- 
solved into  their  simple  constituents,  they  are  found  to  be 
composed  of  carbon,  oxygen,  hydrogen  and  nitrogen,  which 
form  the  vegetable  proximate  principles  ;  together  with  phos- 
phorus, silicon  and  sulphur ;  the  alkalies,  soda,  potassa,  ammo- 
nia ;  the  alkaline  earths,  magnesia,  lime  and  alumina,  and  the 
oxides  of  iron,  and  of  manganese.  The  four  simple  substances, 
which  form  the  proximate  principles,  are  called  the  organic^ 
and  the  remaining  bodies  the  inorganic  constituents  of  plants. 

The  simple  bodies  of  which  vegetables  are  composed,  are, 
of  course,  all  or  nearly  all  derived  from  a  source  foreign  to 
the  plant ;  for  although  the  vital  power,  may  combine  these 
simple  elements,  so  as  to  form  a  great  variety  of  different 
compounds,  it  cannot  create  a  single  particle  of  matter.  The 
view  which  was  formerly  taken,  that  metallic  oxides  were  the 
products  of  the  vital  power,  has  no  foundation,  either  in  fact, 
or  in  philosophy.  Whence  then  do  plants  derive  the  mate- 
rials, out  of  which,  their  vital  functions  build  up  their  vegeta- 
ble structure  ?  In  what  particular  form  do  they  enter  the 
organs  of  plants,  and  what  are  the  changes  which  take  place 
in  their  assimilation  ?  These  questions  have  been  variously 
answered,  and  some  things  are  still  matters  of  controversy.  It 
will  be  necessary  to  devote  this  and  the  following  sections  to  a 
12 


138  BIOLOGY  OF  PLANTS. 

full  discussion  of  the  theories  of  those  chemists  and  physiolo- 
gists, which  are  best  entitled  to  confidence. 

In  the  present  state  of  our  knowledge,  it  will  be  more  use- 
ful to  present  the  arguments  for  and  against  the  most  favor- 
ite theories,  and  to  state  the  practical  deductions  which  natu- 
rally grow  out  of  them. 

I.  Carbon.  The  most  abundant  substance  in  vegetables, 
is  carbon.  From  whence  is  it  derived,  and  what  are  the 
changes  which  take  place  in  its  assimilation  ? 

History.  It  has  been  the  general  opinion  of  agricultural 
writers,  that  vegetable  mould  or  humus  is  the  principal  source 
of  the  carbon  of  plants  ;  and  hence,  the  cause  of  the  fertility 
of  soils. 

Humus  or  mould  is  a  brown  substance,  easily  soluble  in 
alkalies,  and  but  slightly  soluble  in  water.  It  results  from 
the  decomposition  of  vegetable  matter,  when  subjected  to  the 
agency  of  water  and  air,  but  its  formation  may  be  promoted 
by  the  action  of  alkalies,  alkaline  earths,  metallic  oxides,  and 
in  some  cases  by  acids.  Chemists  have  designated  this  sub- 
stance by  several  names  ;  sometimes  including  all  the  decom- 
posed organic  matters  of  the  soil  under  the  term  humus  or 
geine,  and  sometimes  only  the  soluble  parts  of  it.  Berzelius, 
in  1833,  divided  the  organic  matters  of  the  soil  into  extract 
of  humus,  geine  and  carbonaceous  mould ;  and  in  1841  he 
made  the  following  division  ;  extract  of  humus,  humic  acid, 
humin,  crenic  and  apocrenic  acids.  Now  the  gci?ie  of  1833  is 
the  hujnic  acid  of  1841.  Dr.  Dana  calls  all  the  decomposed 
organic  matter  of  the  soil  geine.  This  consists  of  two  parts  ; 
that  which  is  decomposed  by,  or  is  soluble  in  alkalies,  and 
which  is  a  definite  compound,  he  calls  soluble  geine,  and  as 
it  exhibits  the  properties  of  an  acid,  geic  acid,  answering  to 
humic  acid ;  and  that  which  is  insoluble  in  the  same  solvent, 
he  calls  insoluble  geine.  He  also  admits  the  existence  of 
crenic  and  apocrenic  acids. 

Dr.  C  T.  Jackson  denies  the  existence  of  any  such  defi- 


SOURCE  OF  THE  CARBON.  139 

nite  compound  as  soluble  gcine,  but  makes  the  substance  so 
called  consist  of  crcnic  and  apocrenic  acids,  combined  in  part, 
with  bases  forming  in  fact  a  mass  of  salts. 

Liebig  disregards  all  these  different  substances,  and  calls 
the  whole  humus  or  humic  acid.  This  geine  or  humic  acid 
of  soils,  appears  to  be  identical  in  composition  with  a  sub- 
stance, noticed  by  Vauquelin  in  the  bark  of  the  elm,  and 
which  is  the  product  of  vitality  called  ulmin,  and  ulmic  acid. 
It  is  in  fact,  elm-gum,  or  mucillage.  It  was  also  called  humic 
acid.  But  Berzelius  regards  the  ulmic  or  humic  acid  of  soils, 
which  is  the  product  of  decay  or  death,  as  different  from  that 
which  is  the  product  of  life.  There  are  also  several  artificial 
compounds,  which  are  nearly  identical  with  humic  acid. 
"  Ulmin,  humic  acid,  coal  of  humus  and  humin,^^  says  Liebig, 
"  are  names  applied  to  different  modifications  of  humus. 
They  are  obtained  by  treating  peat,  woody  fibre,  or  brown 
coal  with  alkalies  ;  by  decomposing  sugar,  starch,  or  sugar  of 
milk  by  means  of  acids  ;  or  by  exposing  alkaline  solutions  of 
tannic  and  gallic  acids  to  the  action  of  the  air."  The  soluble 
parts  he  calls  huinic  acid;  and  the  insoluble,  humin  or  coal 
of  humus.  Liebig  has  attempted  to  show,  that  these  artifi- 
cial products,  although  they  have  received  the  same  name, 
humic  acid,  are  as  different  in  composition,  as  sugar,  acetic 
acid  and  resin  ;*  and  that  there  is  not  the  slightest  ground 
for  the  belief,  that  any  one  of  them  "exists in  nature  in  the 
form,  and  endowed  with  the  properties,  of  the  vegetable  con- 

*  Thus  the  sulphate  of  potash  and  saw-dust,  when  fused  form  hu- 
mic acid  containing  72  parts  of  C  in  100  (Peligot).  Turf  and  brown 
coal  yield  an  acid  containing  58  parts  of  C  in  100  (Sprengel).  Di- 
lute sulphuric  acid  and  sugar  yield  57  parts  of  C  (Malaguti).  Muriat- 
ic acid  and  sugar  or  starch  yield  64  per  cent,  of  C  (Stein).  Malaguti 
states,  that  humic  acid  contains  an  equal  number  of  equivalents  of  oxy- 
gen and  hydrogen  ;  but  according  to  Sprengel,  the  oxygen  is  in  ex- 
cess, and  Peligot  estimates  the  excess  to  be  14  equiv.  of  oxygen  to 
6  of  hydrogen  ;  but,  Hermann  makes  the  humic  acid  of  soils  to  be 
composed  of  58  parts  of  C,  2.10  of  hydrogen,  and  39.90  of  oxygen. 


140  BIOLOGY  OF  PLANTS. 

stituents  of  mould  ;"  that  is,  he  denies  the  existence  of  these 
substances  in  the  soil,  and  that  they  exert  the  slightest  influ- 
ence upon  vegetation.  But  with  this  exception  of  Liebig  and 
Raspail,  all  chemists  admit  the  existence  of  humic  acid  in 
the  soil.  It  should  be  observed  further,  that  the  humic  acid 
of  soils  is  constant  in  its  composition,  while  that  formed  by 
artificial  processes,  varies  in  the  proportion  of  its  carbon. 

"  Once  for  all,"  says  Dr.  Dana,  when  speaking  of  the  hu- 
mic acid  of  soils,  "  I  consider  ulmin,  humus,  geine,  ulmic 
and  geic  acid  one  identical  substance,  whether  neutral  or 
acid,  its  constitution  ever  one  and  the  same,  subject  to  the 
great  law  of  organic  chemistry,  that  proximate  compounds 
act  as  simple  elements."* 

But  whatever  name  we  give  to  this  substance,  whether  we 
regard  it  as  a  definite  organic  compound  in  the  soil,  gen- 
erally united  to  oxides,  forming  in  fact  a  mass  of  geates,  or 
as  composed  of  several  acids,  which  are  also  combined  with 
similar  bases,  forming  crenates,  apocrenates  and  humates,  or 
whether  it  is  differently  constituted ;  it  has  been  generally 
believed  to  be  the  source  from  whence  plants  derive  most  of 
their  carbon. 

There  is  one  distinguished  chemist,  however,  Liebig,  who 
has  lately  advocated  the  opinion,  that  the  humus  of  soil  does 
not  yield  the  "  smallest  quantity  of  carbon  to  plants,"  and 
"  that  the  only  use  of  it  is,  to  form  a  small  quantity  of  carbonic 
acid,  a  substance  which  exists  in  sufficient  abundance  in  the 
atmosphere,  and  from  which  alone,  all  the  carbon  is  derived." 
This  theory,  with  others,  will  now  be  examined  at  length. 

I  Theory  oj  Liebig.  According  to  this  theory,  the  only 
source  of  the  carbon  of  plants,  is  carbonic  acid,  which  is 
found  either  in  the  atmosphere,  and  absorbed  by  the  leaves 
of  plants,  or  is  dissolved  in  water,  and  enters  by  the  roots. 
In  both  cases,  the  acid  is  decomposed  in  the  leaves,  by  the 

*  For  a  full  history  of  this  substance,  see  Dana's  Muck  Manual, 
p.  72  seq. 


THEORY  OF  LIEBIG.  141 

influence  of  solar  light.  This  theory  differs  from  others,  only 
in  supposing,  that  all  the  carbon  of  plants  is  derived  from  the 
carbonic  acid  of  the  atmosphere.  All  chemists  and  vegetable 
physiologists  fully  agree,  that  a  large  portion  of  the  carbon  is 
thus  obtained. 

Arguments  in  support  of  this  theory.  Liebig  represents 
humic  acid  or  humus,  as  the  only  substance  in  the  soil,  cajja- 
ble  of  yielding  carbon  to  plants ;  and,  as  it  requires  2500  parts 
of  water  to  dissolve  it,  alkalies  or  alkaline  earths  must  com- 
bine with  it,  to  render  it  soluble  and  capable  of  entering  the 
roots.  Now  this  acid  is  a  definite  compound,  and  he  attempts 
therefore,  to  determine  the  exact  quantity  which  will  combine 
with  the  inorganic  base,  which  enter  into  the  composition  of 
vegetables. 

1.  Suppose  that  the  humate  of  lime,  the  most  abundant 
salt- of  humic  acid,  is  the  source  of  the  carbon.  On  the  sup- 
position that  the  lime  remains  fixed  in  the  vegetable  organs, 
it  is  found  by  accurate  calculation,  that  only  Jg  part  of  the 
carbon,  actually  foupd  in  plants,  could  be  introduced  in  this 
way. 

2.  If  we  calculate  the  quantity  of  metallic  oxides  in  wheat 
straw,  and  the  known  quantity  of  humic  acid  required  to  sat- 
urate them,  we  shall  find,  that  the  proportion  of  carbon  intro- 
duced by  this  means,  will  be  as  1  to  17,  or  about  y^  part  of 
the  carbon  which  the  straw  actually  contains. 

3.  Humate  of  lime,  the  most  soluble  of  all  the  salts  of  hu- 
mic acid,  must  first  be  dissolved  in  water,  one  part  of  which 
requires  2500  of  water  for  solution.  Now  if  we  calculate 
the  quantity  of  water  which  falls  on  a  given  surface,  in  one 
season,  and  suppose  all  the  water  to  enter  the  organs  of  plants, 
the  humate  of  lime  which  it  would  carry  with  it,  would  not 
yield  more  than  J^  of  the  quantity  of  carbon  which  is  found 
in  the  corn,  grown  on  the  same  surface.  But  only  a  small 
part  of  the  water  actually  enters  the  roots  of  plants,  and  hence, 

12* 


142  BIOLOGY  OF  PLANTS. 

the  quantity  of  carbon  introduced  by  this  means,  must  be 
much  less. 

4.  Fertile  land  produces  carbon  in  the  form  of  wood,  hay, 
grain,  and  other  kinds  of  growth,  the  bulks  of  which  differ 
in  a  remarkable  degree,  but  the  quantity  of  carbon  yielded  by 
equal  surfaces  is  quite  constant.  On  the  supposition  that 
the  land  is  equally  fertile,  the  w^eights  of  forest  trees,  hay, 
beet  root  and  rye,  growing  on  an  equal  surface,  are  as  2650, 
2500,  20,000,  2580 ;  but  when  these  several  products  are  de- 
composed, the  actual  quantity  of  carbon  in  each  is  about  100 
parts;  hence,  the  quantity  of  carbon  is  not  affected  by  ma- 
nure, as  forest  lands,  meadows  and  cultivated  fields  yield  the 
same  amount.  These  facts  show  that  the  humus  of  the  soil 
is  not  the  source  of  the  carbon* 

Whence  then  is  it  derived?  It  is  universally  admitted, 
that  humus  arises  from  the  decay  of  plants.  No  primitive 
humus,  therefore,  can  have  existed,  for  plants  must  have  pre- 
jeeded  the  humus. 

Now,  whence  did  the  first  vegetables  derive  their  carbon] 
and  in  what  form  is  the  carbon  contained  in  the  atmosphere  ? 
These  two  questions  are  easily  answered,  when  we  consider, 
that  the  atmosphere  contains  carbon  in  the  form  of  carbonic 
acid,  in  nearly  invariable  proportions.  The  carbonic  acid, 
amounts,,  constantly,  according  to  Saussure,  to  0.000415  of 
its  volume,  or  about  y^V^y  P^^^^  ^y  weight,  although  several 
causes  are  constantly  tending  to  increase  it.  The  respiration 
of  animals  throws  off  immense  quantities  into  the  atmos- 
phere. Great  quantities  are  also  evolved  from  volcanic  dis- 
tricts and  from  certain  springs.  It  is  liberated  from  limestone, 
and  other. carbonates,  by  chemical  action;  and,  finally,  the 
process  of  combustion  must  very  much  increase  the  amount. 
By  this  latter  process,  and  by  the  respiration  of  animals,  oxy- 
gen is  consumed ;  but  the  atmosphere  always  contains  the 
same  proportion  of  oxygen,  why  does  not  the  oxygen  dimin- 
ish and  the  carbonic  acid  increase  1  simply  because  plants 


THEORY  OF  LIEBIG. 


143 


absorb  the  carbonic  acid,  assimilate  the  carbon,  and  yield 
back  the  oxygen  to  the  atmosphere,  and  they  must  always 
have  done  the  same. 

This  remarkable  property  of  plants  has  been  demonstrated 
in  the  most  satisfactory  manner  by  Priestley  and  Sennebier. 
The  power  of  decomposing  the  acid  resides  in  the  leaf,  but 
is  exercised  only  when  the  leaf  is  exposed  to  the  light.  This 
power  is  not  dependent  upon  the  connection  of  the  leaf  with 
the  stem,  as  leaves  separated  from  the  stalk,  and  exposed,  in 
an  atmosphere  of  carbonic  acid,  to  the  solar  light,  readily  ab- 
sorb and  decompose  it ;  but  if  the  plant  is  immersed  in  an  al- 
kaline solution,  which  will  prevent  the  carbon  from  being  as- 
similated, no  oxygen  will  be  emitted.  Hence  it  appears,  that 
the  life  of  plants  is  connected  with  that  of  animals,  in  a  most 
simple  manner,  and  for  a  wise  and  sublime  purpose.  Plants 
may  live  without  animals,  but  animals  must  have  organic 
matter  for  their  support.  Plants  purify  the  air,  and  furnish 
an  inexhaustible  source  of  oxygen  gas. 

The  orfy  questions  now  are,  whether  there  is  a  sufficient 
quantity  of  carbonic  acid  in  the  atmosphere  to  supply  the 
wants  of  plants  ;  and  if  so,  whether  it  is  available  ? 

As  to  the  quantity.  We  know  the  exact  weight  of  the 
whole  atmosphere ;  for  every  square  inch,  on  the  surface  of  the 
earth,  weighs  151bs.,  of  which  -jo^^-q  part  by  weight  is  carbonic 
acid.  By  this  data,  the  quantity  of  carbon  in  the  form  of  car- 
bonic acid  amounts  to  nearly  3000  billions  of  pounds ;  a  quan- 
tity more  than  the  weight  of  all  the  plants,  and  all  the  strata 
of  mineral  and  brown  coal,  which  exist  upon  the  earth.  This 
carbon  is,  therefore,  more  than  adequate  for  all  the  purposes 
for  which  it  is  required.  The  proportional  quantity  of  car- 
bon contained  in  sea-water,*  is  still  greater. 

That  this  carbon  is  available  to  plants,  appears  from  the 
fact  that  the  winds,  moving  at  the  rate  of  sixty  miles  per  hour, 

*  10,000  volumes  of  sea-water  contain  620  volumes  of  carbonic  acid. 


144  BIOLOGY  OF  PLANTS. 

are  constantly  mingling  the  top  and  bottom  air,  and  the  car- 
bonic acid  of  the  northern  regions  is  thus  carried  to  the  trop- 
ics, where  a  luxuriant  vegetation  liberates  the  oxygen,  and 
sends  it  back  again  towards  the  poles.  The  leaves,  also, 
which  are  the  organs  of  absorption,  present  a  large  surface,  in 
contact  with  which  the  acid  is  constantly  brought. 

5.  As  the  most  important  function  in  the  life  of  plants  is 
the  separation  of  oxygen  gas,  no  matter  can  be  considered 
nutritious,  or  necessary  to  the  growth  of  plants,  whose  com- 
position is  similar  to,  or  identical  with,  the  vegetable  products. 
Thus  starch,  gum  and  sugar  cannot  be  vegetable  food,  as 
their  assimilation  would  take  place  without  the  separation  of 
oxygen.  Now  humus,  or  decaying  woody  fibre,  contains 
carbon  and  the  elements  of  water,  without  any  excess  of  oxy- 
gen ;  hence  it  resembles  one  class  of  vegetable  products,  and 
cannot,  therefore,  be  assimilated  and  become  the  source  of  the 
carbon. 

6.  The  very  nature  of  decay,  that  is,  of  the  conversion  of 
wood  and  vegetable  matter  into  humus,  shows  that  carbonic 
acid  is  the  only  source  of  the  carbon.  In  the  decay  of  woody 
fibre,  what  are  the  chemical  changes  which  take  place  ? 
Oxygen  is  absorbed  from  the  air,  and  carbonic  acid  is  evolved. 
The  oxygen  of  the  air  combines  with  the  hydrogen  of  the 
wood,  and  the  carbon  and  the  oxygen  of  the  wood  are  evolved 
in  the  form  of  carbonic  acid.  If  the  oxygen  of  the  air  com- 
bined with  the  carbon,  so  as  to  produce  a  genuine  combustion, 
the  carbon  of  the  woody  fibre  would  in  time  be  all  removed. 
But  the  proportion  of  carbon  is  greater  in  humus  than  in 
woody  fibre ;  hence  it  is  a  process  of  oxidation,  while  car- 
bonic acid  is  evolved;  but  after  a  while,  the  attraction  of  the 
oxygen  for  the  hydrogen  is  overcome  by  the  attraction  of  the 
carbon  for  the  same  substance,  and  the  process  of  decay 
ceases.  The  brown  substance  which  remains  is  called 
mould,  and  is  the  product  of  the  complete  decay  of  woody  fibre. 
Alkalies  increase  this  tendency  to  decay,  and  acids  retard  it. 


THEORY  OF  LIEBIG.  145 

When  the  soil  is  stirred,  it  facilitates  the  introduction  of  oxy- 
gen, which  also  hastens  the  process.  How  then  does  the  de- 
caying woody  fibre  act  ?  Simply  by  yielding  carbonic  acid  : 
and  when  any  substance,  as  stagnant  water,  or  the  composi- 
tion of  the  soil,  arrests  the  process  of  decay  by  excluding  the 
air,  then  the  carbonic  acid  is  not  yielded  to  the  roots  of 
plants,  and  the  leaves  turn  yellow  and  fall  off. 

7.  Finally,  that  carbonic  acid  is  the  only  source  of  the 
carbon,  appears  from  the  fact,  that  in  the  "  chemical  trans- 
formations "  which  take  place  in  the  process  of  assimilation, 
the  eifete,  or  excrementitious  matters,  which  are  thrown  out 
by  the  roots,  contain  a  quantity  of  carbon,  nearly  or  quite 
equal  to  that  which  the  humus  yields  in  the  form  of  carbonic 
acid.  This  matter  becomes  humus,  and  is  converted  into 
carbonic  acid  again,  in  the  process  of  decay.  Now  when 
these  excretions  are  added  to  the  carbon,  derived  from  the  roots 
of  plants  and  from  their  leaves,  the  quantity  annually  returned 
to  the  soil,  must  be  greater  than  that  which  is  taken  from  it. 
"  A  soil  receives  more  carbon  in  this  form,  than  its  decaying 
humus  had  lost  in  the  form  of  carbonic  acid." — L. 

From  all  these  facts,  it  appears  evident  that  humus  does 
not  nourish  plants  by  being  taken  up  and  assimilated  in  its 
unaltered  state,  but  by  furnishing  a  slow  and  lasting  source 
of  carbonic  acid.  It  should  be  remarked  in  this  connection, 
that  it  is  only  during  the  period  of  youth,  that  plants  use 
even  the  carbonic  acid  derived  from  the  humus  of  the  soil. 
As  soon  as  their  organs  are  sufficiently  enlarged,  they  de- 
rive their  carbon  wholly  from  the  atmosphere. 

We  have  been  thus  particular  in  giving  the  leading  argu- 
ments by  which  this  theory  is  advocated,  because  of  the  bold- 
ness and  novelty  of  the  views  which  it  contains,  and  also  be- 
cause it  points  out  the  most  important  source  of  the  carbon  of 
plants ;  and  although  it  is  not  true,  as  we  shall  show,  that 
carbonic  acid  is  the  only  source  of  the  carbon,  this  theory 
will  aid  us  in  determining  what  portion  is  derived  from  that 
source. 


146  BIOLOGY  OF  PLANTS. 

Objections  to  the  Theory  of  Liehig.  The  arguments 
by  which  this  theory  is  supported,  are  not  all  well  founded ; 
and  if  they  were,  they  would  not  prove  its  truth,  but  would 
furnish  good  reasons  for  the  opposite  opinion,  that  plants  de- 
rive a  part  of  their  carbon  from  other  sources. 

1.  This  theory  does  not  give  a  correct  view  of  the  compo- 
sition of  humus.  According  to  the  recent  analysis  of  Ber- 
zelius,  the  humus  of  soils,  as  we  have  seen,  is  composed  of 
humin,  extract  of  humus,  humic,  crenic  and  apocrenic  acids, 
and  some  salts.  Dr.  C.  T.  Jackson  makes  the  humus  of  soils 
consist  of  more  than  twenty  substances,  of  which  humic,  cre- 
nic and  apocrenic  acids  are  the  most  important.  These  sub- 
stances are  rich  in  carbon,  containing  from  fifty  to  sixty  per 
cent.  They  are  rendered  soluble  in  water,  by  the  action  of 
the  oxygen  of  the  air  and  of  alkalies ;  they  must  therefore  en- 
ter the  roots  of  plants,  and  may  be  decomposed  in  the  vege- 
table organs,  yielding  their  carbon,  oxygen  and  hydrogen, 
while  the  inorganic  bases  with  which  they  were  united,  may 
be  returned  to  the  soil  as  excretory  matter.  Thus,  according 
to  the  theory  itself,  and  to  other  facts,  the  inorganic  bases, 
which  Liebig  supposes  remmnjixed  in  the  plant,  may  be  the 
means  of  conveying  successive  portions  of  carbon  into  the 
vegetable  organs.  In  fact  the  decomposition  of  salts  by  the 
"  catalysis  of  life"  is  the  most  important  change  which  takes 
place  in  the  soil.  The  bases  are  thus  let  loose  upon  the  hu- 
mus, combine  with  it,  and  the  salts  may  again  be  decom- 
posed. Hence,  a  part  of  the  carbon  must  be  derived  from 
the  humus  of  the  soil. 

2.  But,  on  the  supposition  that  no  larger  quantity  of  carbon 
could  be  introduced,  by  means  of  humic  acid  or  humates,  than 
the  theory  supposes,  the  conclusion  is  still  unavoidable,  that  a 
part  of  the  carbon  is  derived  from  this  source,  or  else,  that  large 
quantities  of  carbon  are  taken  into  the  vegetable  organs  and 
again  rejected,  without  being  decomposed ;  but  in  such  a 
case,  they  must  act  as  poisons,  and  become  a  constant  source 


OBJECTIONS  TO  THE  THEORY  OF  LIEBIG.  147 

of  injury.     Of  course,  the  richer  a  soil  is  in  humus,  the  more 
injurious  must  its  effects  be  upon  the  crop  ! 

3.  This  theory  does  not  give  a  correct  view  of  the  quantity 
of  water  in  the  soil.  Rains  are  by  no  means  the  only  source 
of  water.  All  vegetable  bodies,  according  to  Liebig,  and 
others,  in  the  process  of  decay,  yield  carbonic  acid  and  wa- 
ter. For,  although  water  is  decomposed,  it  is  but  a  small  quan- 
tity, compared  with  that  which  is  formed  by  the  union  of  the 
oxygen  of  the  air  and  the  hydrogen  of  the  vegetable  matter. 
From  this  latter  source,  not  noticed  by  Liebig,  a  quantity  of 
water  is  furnished,  sufficient  to  hold  in  solution  a  larger  quan- 
tity of  humates,  than  the  theory  supposes. 

This  is  a  perfect  answer  to  the  assertion,  that  the  rains  do 
not  furnish  a  sufficient  quantity*  of  water  to  hold  the  humates 
in  solution.  In  fact,  it  is  highly  probable,  that  the  plants,  on 
an  acre  of  soil,  take  up  by  their  roots  and  transpire  through 
their  leaves,  a  larger  quantity  of  water,  during  any  given  time, 
than  falls  during  the  same  time  upon  an  equal  surface.  But 
if  water  dissolves  any  portion  of  the  humates,  it  must  be  the 
means  of  conveying  to  the  plant  a  portion  of  their  carbon. 

4.  This  theory  entirely  overlooks  the  influence  of  living 
plants  upon  the  alkalies  in  the  soil. 

The  vegetable,  in  connection  with  the  soil  and  water,  forms 
a  galvanic  battery,  by  which  the  alkalies  are  eliminated. 
These  alkalies,  coming  in  contact  with  humus  or  geine,  ren- 
der it  soluble.  This  is  a  farther  means  of  introducing  hu- 
mates into  the  organs  of  plants,t  and  hence  a  part  of  the  car- 
bon must  be  derived  from  this  source. 

5.  "Vegetable  and  animial  manures,"  says  Berzelius,  "  be- 
come changed,  after  a  while,  into  crenic,  apocrenic  and  hu- 
mic  acids,  in  order  to  supply  what  has  been  removed  by  the 

*  See  Dana's  Muck  Manual,  p.  225. 

t  See  Dr.  Dana's  Letter  to  Prof  Hitchcock,  in  the  Final  Report  of 
the  Geology  of  Massachusetts.     Also,  Appendix  to  Liebig,  2d  edit. 


148  BIOLOGY  OF  PLANTS. 

crops,  which  have  been  taken  from  the  soil."  Hence  it  would 
seem,  that  these  substances  are  the  sources  of  a  part  at  least 
of  the  carbon,  and  that  it  enters  mostly  in  the  form  of  humates 
{geates),  crenates  and  apocrenates. 

6.  This  theory  is  inconsistent  with  itself  and  with  facts. 
If,  as  Liebig  contends,  plants  give  out  to  the  soil  effete  matter, 
mostly  composed  of  carbon,  this  matter  cannot  affect  th  e 
succeeding  crop  ;  for  if  all  the  carbon  is  derived  from  the  at- 
mosphere, the  excretions  will  not  be  absorbed  in  larger  quan- 
tities than  other  matters,  especially  as  they  are  nearly  insolu- 
ble. But  Liebig  and  others  admit,  and  experience  seems  to 
prove,  that  the  effete  matters  of  one  family,  are  injurious  to 
succeeding  crops  of  the  same  family,  but  useful  to  those  of  a 
different  race. 

On  this  theory  the  fertility  of  soils  does  not  depend,  in  the 
slightest  degree,  upon  the  quantity  of  vegetable  matter,  the 
humus  or  geine ;  a  conclusion  which  is  opposed  to  all  experi- 
ence on  the  subject.  For  it  has  been  observed  by  every  far- 
mer, that  vegetable  substances  are  highly  promotive  of  fertil- 
ity, so  much  so,  that  it  has  long  been  the  effort  of  farmers  to 
convert  their  soils  into  loams  by  the  addition  of  these  sub- 
stances ;  that  is,  by  increasing  the  quantity  of  vegetable  mould 
or  humus.  A  soil  rich  in  humus  or  geine  is  generally  fertile, 
one  destitute  of  it  is  wholly  barren  ;  and  the  degree  of  fertility, 
as  will  be  fully  shown  in  a  future  section,  is  very  much  in  the 
ratio  of  the  soluble  geine  which  the  soil  contains. 

According  to  this  theory,  a  continual  course  of  cropping 
ought  to  increase  the  quantity  of  carbon  in  the  soil,  especially 
as  the  soil  may  be  so  constituted  as  to  contain  but  little  de- 
caying humus  to  supply  carbonic  acid  to  the  roots.  But  we 
know  that  when  afield  has  been  cultivated  for  a  long  period,  and 
the  crops  all  removed,  it  will,  in  the  end,  be  reduced  to  abso- 
lute barrenness ;  and  when  we  look  for  the  cause,  we  find 
the  vegetable  matter  is  mostly  or  quite  removed.  The  effect 
of  manures,  therefore,  in  keeping  up  the  quantity  of  vegetable 


OBJECTIONS  TO  LIEBIg's  THEORY.  149 

mould,  and  with  it,  the  fertility,  proves  conclusively,  that  plants 
derive  their  carbon  from  other  sources  than  carbonic  acid. 
"  A  seed  germinates  in  a  soil  in  which  no  vegetable  matter 
exists;  it  sprouts  vigorously,  increases  then  slowly,  grows 
languidly  at  the  expense  of  the  air ;  and  the  plant  dies  stinted 
or  immature."* 

6.  Finally,  it  appears  upon  a  general  view  of  the  subject, 
that  although  carbonic  acid  is  absorbed  by  the  leaves  and 
roots  of  plants,  and  is  a  source  of  a  large  quantity  of  their 
carbon,  yet  other  substances,  rich  in  carbon,  must  enter 
the  roots  of  plants,  must  be  decomposed,  and  their  carbon 
assimilated. 

The  fact,  that  the  atmosphere  contains  carbon  in  sufficient 
quantities  to  supply  the  whole  vegetation  of  the  globe  with  it, 
does  not  prove  it  the  only  source.  The  fact,  that  the  atmos- 
phere is  not,  in  time,  filled  with  this  acid,  does  not  show  that 
plants  must  derive  all  their  carbon  from  it,  or  else  its  purity 
would  be  destroyed.  There  is  a  vast  ocean  of  water  which 
is  constantly  absorbing  carbonic  acid.  Growing  vegetables  are 
acknowledged  by  all,  to  decompose  a  large  quantity  of  it,  and 
thus  to  contribute  to  the  purity  of  the  atmosphere.  And  this 
process  is  truly  for  a  sublime  purpose  ;  but  yet,  the  necessity 
of  deriving  carbon  from  the  humus  of  the  soil,  is  not,  on  this 
account,  wholly  dispensed  with. 

This  theory,  then,  must  not  be  received  in  the  absolute 
sense,  but  only  as  showing,  in  a  strong  light,  the  principal 
source  of  the  carbon  of  plants ;  while  the  nature  of  humus  is 
such,  according  to  the  theory  itself,  as  to  furnish  abundant 
ground  for  the  opinion,  that  a  part  of  the  carbon  is  derived 
from  that  source.  Although  it  may  be  true,  that  the  whole  of 
the  carbon  was  originally  derived  from  the  atmosphere,  it  is 
not  true  that  any  single  crop  derives  the  whole,  directly,  from 
this  source.  ,.;,<  .  - 

*  Johnson's. Lectures. 

13 


150  BIOLOGY  OF  PLANTS. 

The  other  sources,  from  which  plants  derive  their  carbon, 
have  already  been  pointed  out.  The  humus  of  the  soil  is 
composed  mostly,  as  we  have  seen,  of  humic  or  geic  acid, 
crenic  and  apocrenic  acids.  These  substances  contain  large 
quantities  of  carbon,  generally  in  the  form  of  salts,  which  are 
soluble  in  water.  They  must  enter  the  roots  with  that  liquid, 
and  yield  their  carbon  to  the  plant. 

TTie  proportion  of  carbon  derived  from  the  atmosphere, 
and  from  other  sources,  will  depend  upon  the  nature  and 
age  of  the  plant;  the  quantity  of  food  in  the  soil  or  the 
air;  climate;  quantity  of  light,  and  similar  circumstances. 

We  know,  by  the  observations  of  every  day,  that  fields 
which  are  constantly  covered  with  vegetation,  such  as  pastures 
and  wood  lands,  increase  in  carbon.  They  must  not  only 
take  from  the  air  nearly  the  whole  which  enters  into  their 
substance,  but  they  must  also  add  to  the  quantity  in  the  soil, 
This  certainly  must  be  the  case  in  peat  swamps,  where  the 
vegetable  matter  accumulates  to  a  depth  of  several  feet.  But 
tillage  crops,  as  appears  both  from  observation  and  experi- 
ment, take  more  from  the  soil  than  they  return  to  it.  By  the 
carefully  conducted  experiments*  of  Boussingault,  the  quan- 
tity of  carbon,  which  plants  derive  from  the  atmosphere  dur- 
ing five  years'  rotation,  was  about  two-thirds  of  what  they  con- 
tained ;  but  it  is  evident,  that  a  considerable  quantity  of  car- 
bon in  the  soil,  must  pass  into  the  atmosphere  in  the  form  of 
carbonic  acid ;  and  hence  the  quantity  obtained  from  the  air, 
must  exceed  two-thirds  of  the  whole.t 

*  The  principle,  upon  which  the  experiments  were  conducted,  was, 
to  examine  for  a  series  of  years,  the  quantity  of  carbon  in  the  soil  be- 
fore the  crop,  the  quantity  in  the  crop  itself,  the  quantity  in  the  soil 
after  the  crop  was  removed,  and  the  quantity  added  in  manure. 

t  On  the  supposition,  that  two-thirds  of  the  carbon  is  derived  from 
the  atmosphere,  and  if  we  allow  one  ton  and  a  half  to  be  tlie  average 
quantity  of  dried  produce  on  an  acre  of  surface,  the  quantity  of  car- 
bon would  be  about  1100  pounds. 


ASSIMILATION  OF  CARBON.  151 

If  any  confidence  can  be  placed  in  the  quantity,  which  may 
be  conveyed  to  the  vegetable  organs,  in  the  form  of  humates, 
crenates  and  apocrenates,  we  should  infer,  that  when  these  lat- 
ter substances  were  abundant,  more  than  one  third  might  be  in- 
troduced by  these  means ;  but  when  not  abundant,  much  less 
than  that  proportion  of  the  whole  carbon  which  the  plant 
contains,  would  be  furnished  from  the  soil.  So  far,  then,  as 
the  state  of  our  knowledge  enables  us  to  come  to  any  just  con- 
clusions, the  sources  of  the  carbon  of  plants  are, 

1.  The  carbonic  acid  of  the  atmosphere,  which  is  the  prin- 
cipal source. 

2.  The  humus  of  the  soil,  or  the  humates,  crenates  and 
apocrenates,  found  in  vegetable  mould. 

The  precise  quantity,  from  each  of  these  sources,  it  is  dif- 
ficult to  determine,  as  it  will  vary  with  circumstances ;  hence, 
we  may  conclude  that  plants,  like  animals,  are  capable  of  adapt- 
ing themselves  to  their  situation,  and  of  obtaining,  from  one 
or  the  other  of  these  sources,  the  carbon  which  forms  the 
largest  portion  of  their  substance. 

Theory  of  the  assimilation  of  carbon.  The  changes  wrought 
in  the  vegetable  organs,  upon  the  substances  which  furnish 
carbon  to  plants,  are,  as  yet,  mostly  matters  of  theory. 

We  know,  indeed,  that  carbonic  acid  and  other  substances 
rich  in  carbon,  are  absorbed  by  plants,  and  that  oxygen,  ni- 
trogen, and  some  other  gaseous  bodies,  are  exhaled  by  the 
leaves  and  other  green  parts.  But  the  carbon  does  not  exist 
in  the  plant  in  a  pure  state,  but  in  combination  with  oxygen, 
hydrogen  and  nitrogen,  in  definite  proportions,  forming  the 
vegetable  proximate  principles.  How  then  is  the  carbon  as- 
similated ? 

The  process  of  assimilation  may  be  illustrated  by  chemical 
transformations,  although  the  vital  power,  in  its  mysterious 
operations,  must  be  resorted  to,  in  order  fully  to  explain  the 
phenomena.  "  An  organic  chemical  transformation,  is  the 
separation  of  the  elements  of  one  or  several  combinations, 


152  BIOLOGY  OF  PLANTS. 

and  their  reunion  into  two  or  several  others,  which  contain 
the  same  number  of  elements,  either  grouped  in  another  man- 
ner or  in  different  proportions."* 

"  Of  two  compounds,  formed  in  consequence  of  such  a 
change,  one  remains  as  a  component  part  of  the  blossom  or 
fruit,  while  the  other  is  separated  by  the  roots,  in  the  form  of 
excrementitious  matter.  No  process  of  nutrition  can  he  con- 
ceived to  subsist  in  animals  or  vegetables  icithout  tlic  separa- 
tion of  effete  matters.^''* 

A  transformation  must  take  place,  whenever  there  is  a 
disturbance  of  the  mutual  attraction  which  subsists  between 
the  simple  elements  of  bodies.  The  elements  arrange  them- 
selves, so  as  to  give  rise  to  new  substances,  either  with  or 
without  the  separation  of  one  of  the  elements  of  the  compound. 
"  Hydrocyanic  acid  and  water,  for  example,  contain  all  the 
elements  of  carbonic  acid,  ammonia,  urea,  cyanuric  acid,  cy- 
anilic  acid,  oxalic  acid,  formic  acid,  melam,  ammelin,  me- 
lamin,  azulmin,  mellon,  hydromellonic  acid  and  allantoin."* 
All  these  substances  may  be  obtained  from  hydrocyanic  acid 
and  water,  by  various  chemical  transformations. 

Suppose  now,  that  carbonic,  humic  and  crenic  acids,  were 
to  meet  each  other  in  the  vegetable  organs,  either  in  the  pure 
state,  or  in  the  form  of  their  soluble  salts  (and  they  must  so 
meet),  their  mutual  affinities  would  be  disturbed,  and  their 
elements  arranged,  so  as  to  form  several,  if  not  all,  of  the 
vegetable  compounds.  Each  organ  would  extract  what  food 
was  fitted  for  its  sustenance.  That  is,  one  vegetable  sub- 
stance being  formed,  the  remaining  elements  which  are  not 
assimilated,  would  combine  together  and  be  rejected  at  once 
as  effete  matter  ;  or  by  coming  in  contact  with  another  or- 
gan would  pass  through  another  transformation,  and  so  con- 
tinue on,  until,  being  capable  of  no  farther  transformations, 
the  matter  would  be  separated  from  the  system  by  the  organs 
destined  for  that  purpose.     Thus,  the  useless  matters  rejected 

*  Liebiir. 


ASSIMILATION  OF  CARBON.  153 

by  one  organ,  would  furnish  food  for  a  second  and  a  third. 
The  precise  changes  which  take  place,  are  not  so  easily  detect- 
ed, although  some  of  them  are  easily  deduced,  from  the  known 
character  of  the  substances  which  meet ;  thus,  it  is  easy  to 
see,  that  woody  fibre  may  be  formed  by  the  union  of  the  car- 
bon of  the  carbonic  acid,  with  water,  while  the  oxygen  of  the 
acid,  is  separated  by  the  leaves.  This  process  may  be  ex- 
pressed thus ;  thirty-six  equivalents  of  carbon  derived  from 
thirty-six  equivalents  of  carbonic  acid,  combined  with  twenty- 
two  equivalents  of  hydrogen  and  twenty-two  of  oxygen,  de- 
rived from  twenty-two  equivalents  of  water,  form  woody  fibre, 
with  the  separation  of  seventy-two  equivalents  of  oxygen. 
The  oxygen  which  is  separated,  is  probably  derived  fi-om  the 
carbonic  acid,  as  there  are  just  seventy-two  equivalents  in  thir- 
ty-six of  acid,  although  a  part  may  be  derived  from  the  water. 

Such  transformations  are  constantly  taking  place,  dur- 
ing the  growth  of  plants,  and  the  consequence  is,  that  ex- 
crementitious  matters,  of  different  kinds,  are  thrown  off,  as 
unfit  to  nourish  the  system.  Some  of  these  contain  an  ex- 
cess of  carbon,  others  of  hydrogen,  and  others  still  of  nitro- 
gen and  oxygen.  Some  of  the  matter  is  gaseous,  and  is  giv- 
en off  by  the  leaves  ;  some  of  it  is  liquid,  and  is  ejected  at  the 
roots;  while  part  of  the  effete  matter  is  solid,  and  remains  in 
the  form  of  the  outer  bark.  In  this  respect,  there  is  a  strik- 
ing analogy  between  animals  and  vegetables.  The  kidneys, 
liver  and  lungs  of  animals  are  organs  of  excretion.  The  kid- 
neys separate  all  those  substances,  which  contain  an  excess 
of  nitrogen ;  the  liver,  those  in  which  carbon  is  in  excess, 
and  the  lungs,  those  in  which  oxygen  and  hydrogen  are  most 
abundant.  The  latter  also  exhale  alcohol  and  the  volatile 
oils,  when  taken  into  the  system ;  hence  these  substances  are 
incapable  of  assimilation. 

In  the  process  of  respiration,  the  oxygen  of  the  inspired 
air,  does  not  enter  into  combination  with  the  carbon  in  the 
lungs,  but  combines  with  the  hydrogen  of  the  blood,  while 

13* 


154  BIOLOGY  OF  PLANTS. 

the  carbonic  acid  is  excreted  or  thrown  off.  The  nitrogen- 
ous substances  are  thrown  out  in  a  liquid  form,  by  the  urinary 
organs,  and  the  solid  substances,  by  the  intestinal  canal. 
Hence,  nutrition  in  animal  bodies  is  always  attended  by 
excretions.*     The  same  is  true  of  vegetables. 

The  doctrine  of  transformations,  thus  given,  may  serve  to 
illustrate  the  general  nature  of  assimilation,  so  far  at  least  as 
it  can  be  done  on  strictly  chemical  principles.  Some,  as 
Liebig  would  seem  to  convey  the  idea,  that  the  agency  of  the 
vital poiuer  is  not  required  in  those  changes,  and  that  the  ef- 
fect may  he  fully  accounted  for  on  chemical  principles.  But 
what  chemical  force,  or  what  law  known  to  chemists,  can 
cause  thirty-six  equivalents  of  carbon,  twenty-two  equivalents 
of  hydrogen,  and  twenty-two  equivalents  of  oxygen,  to  com- 
bine and  form  woody  fibre  ?  We  never  see  such  compounds 
formed,  unless  it  Idc  in  the  vegetable  or  animal  organs ;  and 
this  single  fact  shows  conclusively,  that  some  other  pov/er 
than  affinity  is  at  work  to  form  such  combinations. 

We  see  no  reason  for  rejecting  the  theory,  that  the  vital  power 
of  the  plant  may  act  by  its  catalytic  force,  and  decompose  bodies 
which  are  external  to  the  roots,  causing  one  or  more  of  their 
elements  to  enter  their  organs,  and  to  combine  with  substan- 
ces already  introduced,  or  previously  formed.  Such  a  view 
is  rendered  highly  probable,  when  we  consider  the  fact,  that 
the  living  plant  is  a  most  powerful  agent  in  decomposing  the 
soil,  and  obtaining  the  alkali  which  its  wants  may  require. 
Life  is  doubtless  a  powerful  catalytic  force  in  producing  the 
transformations  which  attend  the  process  of  assimilation. 

II.  Source  of  the  Hydrogen  of  Plants.  The  source  of  the 
hydrogen  of  plants  is  easily  determined,  because  there  are 
but  few  substances  which  contain  it  in  sufficient  quantities  to 
supply  the  wants  of  vegetation.  The  chief  sources  of  the  hy- 
drogen are  the  following. 

*  Some  represent  tlie  clmnge  to  be  a  process  of  real  combustion. 
Others  believe,  that  tlie  absorbed  oxygen  unites  with  the  carbon  in  the 
course  of  tlie  circulation. 


SOURCES  OF  HYDROGEN.  155 

1.  Water,  which  is  composed  of  eight  parts  of  oxygen  and 
one  of  hydrogen.  Water  pervades  the  atmosphere  in  the 
form  of  vapor,  is  deposited  in  dew  or  rain,  and  absorbed  by 
the  leaves  of  plants.  It  is  also  taken  in  by  the  roots,  and 
forms  a  large  portion  of  the  sap.  When  we  call  to  mind  the 
fact  of  its  remarkable  tendency  to  pass  through  transforma- 
tions, there  can  be  no  doubt,  but  that  it  furnishes  the  largest 
portion  of  the  hydrogen  of  plants. 

2.  Ammonia  is  another  substance  which  contains  hydrogen. 
It  is  always  present  in  fermenting  manures,  and  in  the  atmos- 
phere. It  must,  like  water,  be  absorbed  by  the  leaves  of 
plants,  and  by  their  roots ;  and  as  it  is  similar  to  water  in  the 
facility  with  which  it  is  decomposed,  it  must  furnish  hydro- 
gen to  the  vegetable  products.  Hence  one  reason  for  its 
powerful  effects  upon  vegetation. 

3.  Light  carbureted  hydrogen  is  found  in  the  atmosphere 
and  in  the  soil,  and  may  be  the  source  of  a  part  of  the  hydro- 
gen of  plants ;  although  it  is  doubtful,  whether  they  draw 
upon  this  source,  when  there  are  at  hand,  more  abundant  and 
far  better  sources.  It  may,  however,  be  decomposed  in 
the  air  by  electric  discharges,  and  resolved  into  carbonic 
acid  and  water. 

4.  Geine  or  humus  of  soils  contains  hydrogen,  in  the  form 
of  humic,  crenic  and  apocrenic  acids.  These  substances  en- 
ter the  organs  of  plants,  and  may  yield  a  large  portion  of  the 
hydrogen.     Liebig  derives  the  hydrogen  wholly  from  water. 

III.  Source  of  the  Oxygen  of  Plants.  Oxygen  may  be  de- 
rived from  several  sources. 

1.  The  atmosphere  contains  twenty-one  parts  of  oxygen  in 
one  hundred,  and  as  the  leaves  of  plants  are  known  to  absorb 
it  (p.  75),  they  obtain  a  part  of  their  oxygen  from  this  inex- 
haustible source. 

2.  Water  contains  eight  parts  in  nine  of  oxygen.  This  is 
absorbed  both  by  the  leaves  and  roots  of  plants  in  large 
quantities,  and  is  doubtless  the  principal  source  of  the  oxygen, 
as  well  as  the  hydrogen  of  vegetable  bodies. 


156    *  BIOLOGY  OF  PLANTS. 

3.  Carbonic  acid  contains  sixteen  parts  in  twenty-two  of 
oxygen,  and  is  a  further  source  of  this  substance. 

4.  Gcinc  or  humus  contains  oxygen,  which  in  the  processes 
of  vegetation,  is  brought  into  contact  with  the  vegetable  or- 
gans, and  may  thus  be  the  source  of  a  portion  of  the  oxygen 
which  plants  contain. 

5.  Nitric  acid  may  be  still  another  source,  and  perhaps 
several  other  acids,  as  the  carbonic,  phosphoric  and  sulphu- 
ric, which  are  known  to  exist  in  all  soils. 

IV.  Theory  of  the  A  ssimilation  of  Oxygen  and  of  Hydro- 
gen. Woody  fibre,  which  is  the  solid  part  of  plants,  and  is 
the  most  abundant  of  the  products  of  vegetables,  is  composed 
of  carbon,  with  oxygen  and  hydrogen  in  the  proportions  to 
form  water  ;  that  is,  if  the  hydrogen  and  oxygen  were  to  com- 
bine, water  would  be  formed  and  carbon  left  in  a  free  state  ; 
or  the  composition  may  be  represented  by  the  elements  of 
carbonic  acid,  with  a  certain  quantity  of  hydrogen. 

Now  the  wood  may  be  formed  by  the  decomposition  of 
carbonic  acid ;  the  carbon  uniting  with  the  elements  of  water, 
and  the  oxygen  escaping  as  effete  matter ;  or,  what  is  more 
probable,  the  carbonic  acid  may  combine  with  the  hydrogen 
of  the  decomposed  water,  while  the  oxygen  of  the  water 
escapes.  In  either  case,  the  quantity  of  oxygen  separated 
would  be  exactly  the  same. 

But  there  are  other  compounds  (as  the  acids),  in  which  oxy- 
gen is  in  excess  ;  in  the  process  of  their  formation,  therefore, 
less  oxygen  would  be  separated.  In  case  oxygen  is  in  less 
quantity  than  in  the  relative  proportion  to  form  water,  as  it 
is  in  alkalies  and  neutral  substances,  such  as  starch,  sugar, 
wax  and  all  resinous  bodies,  then,  in  the  processes  of  assimi- 
lation, much  more  oxygen  would  be  separated.  Such  sub- 
stances yield  a  larger  quantity,  or  all  of  the  oxygen,  both  of 
the  carbonic  acid  and  of  the  water.*      If  this  is  a  true  rep- 

*  The  following  table  of  Liebig,  illustrates  still  further  the  changes 


THEORY  OF  ASSIMILATION.  157 

resentation  of  the  changes  which  actually  take  place  in  the 
assimilation  of  oxygen  and  hydrogen,  it  proves  conclusively 
that  the  vital  power  is  capable  of  reversing  chemical  laws. 
For  this  process  differs  entirely  from  ordinary  chemical  com- 
binations ;  thus,  for  example,  when  carbonic  acid,  zinc  and 
water  are  mingled,  hydrogen  is  separated ;  but  in  the  process 
of  vegetation,  oxygen  is  separated  from  the  living  plant,  and 
given  back  to  the  atmosphere. 

In  the  process  of  decay,  oxygen  is  returned  to  the  atmos- 
phere in  the  form  of  carbonic  acid,  and  is  absorbed  from  the 
air  to  form  water ;  hence,  the  process  of  nutrition  and  decay 
are  exactly  opposite. 

This  theory  serves  rather  to  illustrate  the  nature  of  the 
changes,  than  to  point  out  the  exact  changes  which  take 
place.  In  a  similar  way,  it  might  be  shown  what  changes 
may  take  place,  when  other  substances  containing  oxygen  and 
hydrogen  are  taken  into  the  vegetable  organs.  It  is  there- 
effected  in  assimilation,  on  the  supposition  that  the  carbon  is  derived 
from  carbonic  acid,  and  the  oxygen  and  hydrogen  from  the  water. 

36  eq.  carbonic  acid  and  36 eq.  hydrogen  derived  >       c- 

from  36  eq.  vi^ater  5 

with  the  separation  of  72  eq.  oxygen. 
36  eq.  carbonic  acid  and  30  eq.  hydrogen  de-  )       o^      ? 

rived  from  30  eq.  water  \^  =  Starch, 

with  the  separation  of  72  eq.  oxygen. 
36  eq.  carbonic  acid  and  16  eq.  hydrogen  de-  >       ^  ,,  -j 

rived  from  16  eq.  water  \^=  Tannic  Acid, 

with  the  separation  of  64  eq.  oxygen. 
36  eq.  carbonic  acid  and  18  eq.  hydrogen  de-  )       ^    .     •     ^  • » 
rived  from  18  eq.  water  \^=  Tartaric  Acid, 

with  the  separation  of  45  eq.  oxygen. 
36  eq.  carbonic  acid  and  18  eq.  hydrogen  de-  >        ,,  ,.     ^  ., 
rived  from  18  eq.  water  ^  =  Malic  Acid, 

with  the  separation  of  54  eq.  oxygen. 
36  eq.  carbonic  acid  and  24  eq.  hydrogen  de-  >       r^i   j-^r 

rived  from  24  eq.  water  }^  =  Od  of  Turpentine. 

with  the  separation  of  84  eq.  oxygen. 


158  BIOLOGY  OF  PLANTS. 

fore  highly  probable,  that  plants  derive  their  oxygen  and  hy- 
drogen, as  well  as  their  carbon,  from  several  sources  ;  and 
that  these  two  substances  enter  the  vegetable  organs  in  the 
form  of  water ;  of  geine  or  humic,  crenic  and  apocrenic 
acids  ;  of  ammonia ;  of  common  air ;  and,  probably,  of  sev- 
eral acids. 

V.  Source  and  Assimilation  of  the  Nitrogen  of  Plants,  It 
was  formerly  supposed,  that  nitrogen  existed  in  only  a  few 
plants,  but  it  is  now  established  that  it  exists  in  all.  "  It 
exists  in  every  part  of  the  vegetable  structure."*  The  quan- 
tity, however,  is  very  small,  compared  with  the  other  ingre- 
dients of  the  vegetable  principles.  Hay,  dried  at  240°  F., 
contains  but  IJ,  oats  2j,  and  potatoes  1^  per  cent.  In  the 
ordinary  state  in  which  these  substances  are  found,  they  must 
contain  a  much  less  quantity. 

This  quantity  is  small  only  in  comparison  with  the  other 
organic  constituents,  for  if  we  calculate  the  quantity  of  nitro- 
gen in  an  average  crop  of  hay  and  grain  grown  on  three  hun 
dred  acres  of  land,  it  will  amount  to  eight  tons.t 

This  relatively  small,  but  absolutely  large  quantity  of  ni- 
trogen is  of  the  highest  importance  to  vegetation.  In  fact 
the  value  of  manure  has  been  estimated  by  its  power  of  yield- 
ing nitrogen  in  the  form  of  ammonia.|  The  body  which  ex- 
ists in  the  smallest  quantity  in  the  vegetable  products,  is  just 
as  necessary  to  their  formation,  as  that  which  is  most  abun- 
dant. It  has  been  due  to  a  neglect  of  this  principle  that  so 
little  effort  has,  as  yet,  been  made  to  supply  plants  directly 
with  this  substance.  Whence,  then,  do  plants  derive  their  ni- 
trogen 1     The  following  are  the  principal  sources. 

*  Liebig. 

t  A  ton  of  hay  contains  about  30  lbs.  of  nitrogen  ;  but  tlic  quantity 
depends  very  much  upon  the  kind  of  crop.  Red  clover  contains 
double  the  quantity  of  nitrogen  which  common  hay  does  ;  hence,  an 
acre  yielding  three  tons  would  require  180  lbs.  of  nitrogen. 

X  Dana, 


SOURCES  OF  NITROGEN.  159 

1.  The  atmosphere  contains  seventy-nine  parts  of  nitro- 
gen in  one  hundred,  and  as  it  is  thus  brought  into  direct  con- 
tact with  the  organs  of  plants,  either  as  a  gas,  or  dissolved  in 
water,  it  must  be  absorbed.  Hence  some  have  supposed  it 
possible,  that  a  part  of  that  found  in  vegetable  bodies  is  de- 
rived from  that  source.*  But  the  nitrogen  of  the  air  possesses 
such  inert  and  indifferent  properties,  as  to  render  it  nearly  cer- 
tain, that  it  is  not  assimilated  directly ;  although  we  cannot 
say  what  the  vital  power  may  effect.  It  is  probable,  however, 
that  nitrogen  enters  plants  in  some  of  its  combinations.  The 
question  whether  it  came  originally  from  the  atmosphere,  is 
quite  different  from  the  one  now  under  consideration — the 
immediate  source  of  it. 

2.  Ammonia,  as  we  have  seen  p.  81,  is  produced  in  consid- 
erable abundance.  It  must  be  brought  into  contact  with  the 
leaves  and  roots  of  plants,  and  enter  into  their  organs.  It  is 
composed  of  fourteen  parts  of  nitrogen  and  three  of  hydrogen. 
That  plants  derive  a  part  of  their  nitrogen  from  it,  appears 
exceedingly  probable  from  the  following  considerations. 

(1)  Ammonia  is  found  in  the  sap  of  trees,  and  in  the  juices 
of  all  vegetables.  *'  The  products  of  the  distillation  of  flowers, 
herbs  and  roots,  with  water,  and  all  extracts  of  plants  made 
for  medicinal  purposes,  contain  ammonia.  Ammonia  exists 
in  every  part  of  plants,  in  the  roots  (as  in  beet-root),  in  the 
stem  of  the  maple-tree,  and  in  all  blossoms  and  fruit  in  an 
unripe  condition."!  In  these  cases  ammonia  may  possibly 
be  formed  by  the  living  power,  or  it  may  be  the  effete  matter 
arising  from  transformations ;  but  that  such  is  the  fact  is  ex- 
tremely doubtful. 

(2)  That  ammonia  yields  nitrogen  to  plants,  is  highly  pro- 
bable from  the  action  of  animal  manures.  Gluten  is  a  sub- 
stance containing  the  largest  quantity  of  nitrogen  in  wheat,  rye 
and  barley,  and  is  found  in  different  proportions.  The  more  ani- 
mal manure  there  is  employed  in  the  cultivation  of  these  grains, 

*  Johnson.  t  Liebig. 


160  BIOLOGY  OP  PLANTS. 

the  greater  is  the  proportion  of  gluten  which  they  contain.  Now 
animal  manures  derive  their  special  efficacy  from  the  ammonia 
they  produce  ;  and  it  is  found,  that  the  proportion  of  gluten 
depends  upon  the  capacity  of  the  manure  to  form  it.  Thus, 
putrid  urine  and  human  excrements  will  produce  much  more 
ammonia  than  cow-dung  or  vegetable  matter ;  and  hence 
their  peculiar  efficacy.  The  guano,  which  forms  a  stratum  of 
sixty  or  eighty  feet  in  thickness  in  the  South  Sea  Islands,  and 
which  is  composed  of  the  excrements  of  sea  fowls,  owes  its 
fertile  properties,  in  part,  to  the  large  quantity  of  ammonia 
which  it  contains.  This  manure  is  an  article  of  commerce, 
and  is  placed  on  the  barren  soils  of  Peru,  where  it  produces 
the  most  surprising  effects.  It  is  composed  mostly  of  urate, 
phosphate,  oxalate  and  carbonate  of  ammonia,  with  a  few 
earthy  salts. 

Human  urine  contains  nitrogen,  in  the  phosphates  and  in 
the  urea;  the  latter,  by  putrefaction,  is  converted  into  car- 
bonate of  ammonia.  Now  it  is  well  established,  that  human 
urine  is  the  most  powerful  manure  for  those  vegetables  vv  hich 
contain  a  large  quantity  of  nitrogen.  The  urine  of  herbi- 
ferous  animals  contains  hippuric  acid,  a  substance  which  is 
easily  decomposed  into  benzoic  acid  and  ammonia. 

(3)  The  powerful  influence  of  the  salts  of  ammonia,  is  part- 
ly accounted  for  on  the  supposition,  that  they  yield  nitrogen 
to  plants.  The  kind  of  influence  they  exert  gives  force  to 
this  position  ;  for  the  carbonate  and  sulphate  of  ammonia  in- 
crease the  quantity  of  vegetable  products,  which  require  the 
largest  quantity  of  nitrogen;  that  is,  the  gluten  and  vegetable 
albumen. 

Ammonia,  in  cool  countries,  is  the  last  product  of  the  pu- 
trefaction of  animal  bodies.  A  generation  of  a  thousand  mil- 
lions of  men  are  renewed  every  thirty  years,  and  thousands  of 
animals  cease  to  live,  and  are  produced  in  a  much  shorter 
period,  whence  the  nitrogen  they  contained  during  life  ?  All 
animal  bodies  yield  ammonia  to  the  atmosphere,  hence  it  must 


SOURCE  OF  NITROGEN.  161 

always  exist  in  rain  and  snow  water.  It  is  the  simplest  of 
the  compounds  of  nitrogen.  Nitrogen  has  for  hydrogen  the 
most  powerful  affinity.  It  is  capable  of  being  held  in  solu- 
tion in  water,  and  readily  enters  into  combination  with  car- 
bonic, sulphuric  and  muriatic  acids,  and  by  all  these  means  it 
becomes  fixed  in  the  soil.  A  certain  portion  of  the  ammonia 
which  falls  in  rain  water  evaporates,  but  some  of  it  must  en- 
ter the  organs  of  plants,  and  by  entering  into  new  combina- 
tions in  the  different  organs,  produces  albumen,  gluten,  qui- 
nine, morphia,  cyanogen,  and  a  number  of  other  compounds 
containing  nitrogen. 

(5)  Finally,  if  we  add  to  these  considerations  the  fact,  that 
ammonia  is  found  in  the  atmosphere,  that  it  is  constantly 
produced  in  the  soil,  and  must  enter  the  organs  of  plants, 
where,  owing  to  its  easy  decomposition,  its  nitrogen  must  be 
assimilated,  it  becomes  certain  that  it  yields  nitrogen  in 
the  processes  of  nutrition. 

The  quantity  of  nitrogen  which  plants  derive  from  this 
source  cannot  be  determined.  Liebig  attempts  to  prove,  that 
ammonia  is  the  only  source  of  the  nitrogen.  He  also  attempts 
to  explain  the  utility  of  gypsum,  burned  clay,  powdered  char- 
coal and  humus,  on  the  principle  that  these  substances  absorb 
ammonia  from  the  atmosphere,  and  fix  it  in  the  soil.  The 
carbonate  of  ammonia,  which  is  diffused  through  the  soil  and 
dissolved  in  water,  is  decomposed  by  the  gypsum,*  and  the 
resulting  sulphate  of  ammonia  yields  its  nitrogen  to  the  plant 
as  its  wants  demand.  As  water  is  necessary  to  the  decom- 
position of  the  carbonate  by  the  gypsum,  its  influence  is  not 
observed  on  dry  fields.  The  other  substances  mentioned, 
act  by  absorption,  condensing  the  ammonia  in  their  pores. 
The  arguments  brought  in  favor  of  this  theory,  are  not  all 
of  them  well  founded ;  and  if  they  were,  would  not  prove  it 

*  One  bushel  of  plaster,  on  this  theory,  would  fix  a  quantity  of  am- 
monia, equal  to  6*250  pounds  of  horse  urine,  and  every  pound  of  ni- 
trogen would  produce  100  pounds  of  hay  or  grain, 
14 


162  BIOLOGY  OF  PLANTS. 

true.  Thus,  for  example,  it  is  asserted,  that  the  quantity  of 
nitrogen  removed  from  a  well  conducted  farm,  in  the  form  of 
cattle  and  grain,  must  be  greater  than  that  returned  in  the 
excrements.  But  Dana  has  shown,  by  direct  experiment, 
that  the  quantity  of  nitrogen  in  the  excrements  of  animals,  is 
nearly  double*  that  found  in  the  food,  and  hence  the  quanti- 
ty returned  to  the  soil  is  constantly  increasing. 

The  fact  that  ammonia  is  found  in  the  atmosphere,  that  it 
results  from  the  putrefaction  of  animal  bodies,  and  that  it  is 
found  in  the  sap  of  trees,  does  not  prove  that  plants  derive 
all  their  nitrogen  from  it. 

But  one  of  the  strongest  objections  to  this  theory,  is  the  fact, 
that  in  warm  climates,  where  vegetation  is  most  flourishing, 
the  process  of  putrefaction  in  animal  bodies,  produces  nitric 
acid,  instead  of  ammonia ;  hence  this  latter  substance  will  be 
found  in  the  least  abundance,  where  the  largest  quantity  is 
needed,  and  where  it  is  actually  consumed,  if  this  theory  is  true. 
"  No  conclusion,"  says  Liebig,  ''  can  then  have  a  better  foun- 
dation than  this,  that  it  is  the  ammonia  of  the  atmosphere, 
which  funishes  nitrogen  to  plants ;"  and  we  may  add,  no  con- 
clusion is  better  established  than  this,  that  ammonia  does  not 
furnish  plants  with  the  whole  of  th^ir  nitrogen. 

Whatever  reasons  there  may  be  for  rejecting  the  theory 
which  derives  all  the  carbon,  oxygen  and  hydrogen  of  plants 
from  carbonic  acid  and  water,  we  have  equally  good  reasons 
for  the  belief,  that  ammonia  does  not  furnish  plants  with  all 
the  nitrogen  which  they  contain. 

"  If  it  be  true,"  says  Daubeny,  ''  as  Liebig  has  endeavored 
to  establish,  that  plants  obtain  everything,  except  their  alka- 
line and  earthy  constituents,  from  the  atmosphere,  what,  it 
may  be  asked,  becomes  of  the  theory  that  attributes  the  wifit- 
ncss  of  a  soil  for  yielding  several  successive  crops  of  the 
same  plant,  to  the  excretions  given  out  by  its  roots  ?     For  if 

*  Dana's  Muck  Manual,  p  136. 


SOURCE  OF  THE  NITROGEN.  163 

plants  receive  the  whole  of  their  volatizable  ingredients  from 
the  atmosphere,  these  excrementitious  matters,  being  com- 
posed chiefly  of  carbon,  hydrogen  and  oxygen,  will  not  be 
absorbed,  and  therefore  cannot  affect  the  succeeding  crop.^"* 

If  the  theory  is  true,  which  derives  all  the  organic  constitu- 
ents from  carbonic  acid,  ammonia  and  water,  a  plant  ought 
to  grow  in  a  purely  earthy  soil,  when  supplied  with  ammonia. 
But  no  instance  has  been  produced,  and  it  is  yet  doubtful, 
whether  the  experiment  would  succeed  if  tried. 

The  forms  in  which  ammonia  enters  the  organs  of  pi  ants, 
are  probably  various.  It  may  enter  uncombined,  simply  dis- 
solved in  water,  and  be  assimilated  in  a  manner  similar  to  oxy- 
gen, carbon  and  hydrogen,  p.  156.  But  it  probably  enters  as  a 
salt,  that  is,  in  combination  with  acids.  Dr.  C.  T.  Jackson 
supposes,  that  "  the  carbonate  of  ammonia  acts  upon  the  or- 
ganic matters  of  the  soil,  and  renders  the  organic  acids  neu- 
tral and  soluble  ;  decomposes  and  renders  inert,  noxious, 
metallic  salts  and  other  compounds."  Dr.  Dana  supposes, 
that  ammonia  combines  with  the  geine  to  form  a  soluble 
compound,  and  also  acts  by  its  presence  to  convert  vegetable 
matters  into  geine.  In  either  case,  it  would  be  introduced 
into  the  organs  of  plants,  and  its  nitrogen  assimilated. 

It  has  been  supposed  by  some,  that  the  powerful  influence 
of  ammonia  was  due  to  its  stimulating  properties,  but  others 
have  doubted  such  influence;  among  the  latter  is  Liebig, 
and  among  the  former,  Berzelius.  The  influence  of  light, 
heat  and  electricity  would  lead  to  the  opinion,  that  the  vital 
power  of  plants  is  capable  of  being  excited,  in  a  manner 
analogous  to  that  of  animals. 

If  plants  do  not  derive  all  their  nitrogen  from  ammonia, 
what  other  sources  are  there  from  which  it  can  be  derived  ? 
We  have  already  observed,  that  the  decomposition  of  vegeta- 
ble matters  forms, 

3.  Geine  or  humus,  which  may  be  a  further  source  of  nitro- 
gen.    Humus  consists  of  humic,  crenic  and  apocrenic  acids. 


164  BIOLOGY  OF  PLANTS. 

Humic  acid  is  composed  of  hydrogen,  oxygen  and  carbon. 
Crenic  acid  is  composed,  according  to  Hermann,  of  forty- 
two  parts  by  weight  of  carbon,  sixteen  of  hydrogen,  four- 
teen of  nitrogen,  forty-eight  of  oxygen.  Apocrenic  acid  is 
composed  of  eighty-four  parts  of  carbon,  fourteen  of  hydro- 
gen, forty-two  of  nitrogen,  and  twenty-four  of  oxygen.  These 
latter  acids  are  soluble  in  water,  even  when  combined  with 
bases,  and  contain  a  quantity  of  nitrogen,  which  must  enter 
the  organs  of  plants.  We  have  then,  only  to  suppose  similar 
organic  transformations,  in  order  that  their  nitrogen  may  be 
assimilated  to  the  vegetable  organs.  As  a  part  of  the  carbon 
is  derived  from  the  soil,  so  a  part,  at  least,  of  the  nitrogen 
may  be  derived  from  the  same  source. 

The  influence  of  crenate  of  lime  (which  is  sometimes 
found  in  the  sub-soil)  upon  clover,  favors  the  idea,  that  it 
furnishes  a  quantity  of  the  nitrogen  to  seeds,  fruits,  and  other 
parts  of  vegetables ;  for  it  is  found  that  clover  contains  nearly 
double  the  quantity  of  nitrogen  \vhich  is  found  in  many  other 
grasses. 

4.  Nitric  acid.  The  putrefaction  of  animal  bodies,  yields 
large  quantities  of  nitric  acid,  especially  by  the  fermentation 
of  manures.  This  acid  combines  with  potash,  soda  and  am- 
monia, to  form  salts,  which  are  found,  more  or  less  abundant, 
in  all  fermented  manures.  The  salts  are  soluble  in  water,  and 
must  enter  the  vegetable  organs.  The  acid  is  composed  of 
fourteen  parts  of  nitrogen  and  forty  of  oxygen.  Here,  then, 
is  another  source  of  the  nitrogen  of  plants.  That  plants  de- 
rive a  part,  at  least,  of  their  nitrogen  from  this  source,  is 
proved  by  the  most  incontestable  facts. 

Daubeny  has  shown,  that  nitrate  of  soda,  placed  upon  lands 
sown  with  wheat,  increased  the  gluten  of  the  wheat  4.25  per 
cent.,  and  the  albumcnl  0.75  per  cent.  The  gluten  and 
albumen  contain  great  quantities  of  nitrogen,  and  will  be 
abundant  in  the  seed,  in  proportion  to  the  proper  sup})ly  of 
matters  from  which  they  may  obtain  it.     Whence  did  they 


SOURCE  OF  THE  NITROGEN.  165 

obtain  this  additional  supply  of  nitrogen,  but  from  the  nitric 
acid  1  Nitrate  of  potash  produced  a  similar  effect.  It  is 
well  known  what  a  powerful  effect  salts  of  nitric  acid,  espe- 
cially salt-petre  or  nitre,  have  upon  the  growth  of  vegetables. 
This  influence  must  be  due  to  the  nitrogen  which  is  fur- 
nished to  the  gluten,  vegetable  albumen,  and  other  products 
of  the  vital  power. 

Upon  the  whole,  then,  it  is  highly  probable,  that  plants  de- 
rive their  nitrogen  from  ammonia,  crenic,  apocrenic  and  ni- 
tric acids,  and  that  vegetation  will  be  abundant  in  proportion 
as  these  substances  are  supplied  to  the  roots  of  plants.  They 
are  not,  however,  introduced  in  their  pure  state,  but  are  com- 
bined with  inorganic  bases,  in  the  form  of  salts,  and  are  de- 
composed, and  their  elements  assimilated  by  chemical  and 
vital  forces.* 

But  whatever  theories  we  may  form  on  this  subject,  upon 
the  source  and  assimilation  of  the  carbon,  hydrogen,  oxygen 
and  nitrogen  of  plants,  one  thing  is  certain,  that  the  farmer 
must  supply  vegetable  and  animal  manures  which  contain 
these  elements,  or  the  carbonic  acid,  water  and  ammonia  of 
the  atmosphere,  will  not  be  gathered  into  the  form  of  vegeta- 
ble productions.  The  necessity  of  supplying  the  soil  with 
manure,  cannot  be  set  aside,  by  any  theories  of  the  source 
from  which  plants  derive  their  support ;  and  the  best  theory 
is  that  which  shall  best  explain  the  facts,  and  point  out  the 
most  direct  and  efficient  means  for  increasing  the  quantity 
and  quality  of  the  productions  of  the  farm.  And  we  believe 
it  will  be  found  in  the  end,  that  plants  derive  their  carbon,  hy- 
drogen, oxygen  and  nitrogen  from  the  several  sources  named, 
and  that  they  are  endowed  with  the  power  of  adapting  them- 
selves to  circumstances,  so  as  to  select  a  greater  or  less  quan- 
tity from  each  source ;  but  that  one  alone  will  not  support 


*  Since  writing  the  above,  I  have  received  two  works,  Johnson's 
Lectures,  and  Dana's  Muck  Manual,  which  substantiate  the  views 
given  in  the  text. 

14* 


166  BIOLOGY  OF  PLANTS. 

their  organs  in  a  vigorous  state  of  growth,  and  enable  them 
to  attain  their  highest  perfection. 


Sect.  4.  Definitions. — Source  and  Assimilation  of  the  inor- 
ganic Constituents  of  Plants. 

Potash  or  potassa  (KO=47.15)  is  composed  of  the  metal  po- 
tassium and  oxygen,  one  equivalent  of  each  ;  of  course  its  com- 
bining immber  is  8-f-39=47.  This  substance  is  well  known. 
It  is  found  in  all  plants.  It  is  a  solid,  easily  soluble  in  water, 
caustic  to  the  taste,  eminently  alkaline  in  all  it  properties  and 
relations. 

Carbonates  of  potassa  are  known  to  us  under  the  name  of  pot 
and  pearl-ashes,  and  saleratiis.  The  nitrate  of  potassa  is  known 
as  nitre  and  salt-petre.  All  the  salts  of  this  alkali  are  useful 
substances. 

Soda  (NaO.31.3)  is  an  alkali  similar  to  potassa.  It  is  com- 
posed of  8  parts  of  oxygen,  and  23.3  of  the  metal  sodium  ;  hence 
its  equivalent  is  31.3  and  its  symbol  is  NaO.  It  is  a  white  or 
gray  solid,  very  soluble  in  water,  caustic  to  the  taste,  and,  com- 
bined with  acids,  forms  a  large  class  of  salts. 

The  nitrate  of  soda,  called  cubic  nitre,  is  similar  in  its  chemical 
properties  to  nitrate  of  potassa.  The  carbonate  of  soda  is  well 
known,  as  the  substance  used  for  soda  powders.  The  sulphate 
of  soda  is  the  well  known  substance  Glauber'' s  salts. 

Common  salt  is  a  chloride  of  sodium,  but  when  it  is  dissolved 
in  water,  or  when  the  chlorine  is  removed,  the  metal  sodium 
immediately  combines  with  oxygen,  if  water  is  present,  and 
forms  soda.  The  chlorine  unites  with  the  hydrogen  of  the  wa- 
ter, and  forms  muriatic  acid;  these  may  then  combine,  and  form 
hydrochlorate  of  soda. 

Magnesia  (MgO.20.7)  is  a  white  powder,  of  an  earthy  appear- 
ance, known  in  the  shops  as  calcined  magnesia.  It  is  comi)osed 
of  a  peculiar  metal,  magnesium,  12.7  parts  by  weight,  and  8 
parts  of  oxygen.  Its  symbol  is  MgO.  It  is  very  infusible  and 
slightly  soluble  in  water,  rc({uiring  5142  times  its  weight  of  wa- 
ter, at  ()0°  F.,  and  36,000  of  boiling  water  to  dissolve  it.  AVhen 
exposed  to  the  air,  it  absorbs  carbonic  acid  and  is  converted  into 
tlw  carbonate  of  magnesia,  also  a  white  powder,  very  insoluble 
in  water.  Phosphate  of  magnesia  is  a  comi)ound  of  phosphoric 
acid  and  magnesia,  and  has  not  been  fully  examined.  Sul- 
phate of  magnesia  is  the  common  Epsom  salts. 


DEFINITIONS  AND  DESCRIPTIONS.  167 

Lime  is  composed  of  the  white  metal,  calcium  20.5  parts, 
and  8  parts  of  oxygen.  It  is  a  protoxide  of  calcium,  and  is 
thus  represented,  CaO.=28.5.  Lime  is  a  grayish  white 
solid,  caustic,  acrid  and  alkaline  to  the  taste.  It  has  a  strong 
affinity  for  water,  with  whicli  it  combines,  attended  with  the 
evolution  of  much  light  and  heat,  and  forms  a  bulky  hydrate, 
called  slacked  lime.  It  has  a  strong  affinity  also  for  several  acids, 
with  which  it  combines.  The  carbonate  oj  lime  is  the  common 
limestone  and  marble.  Sulphate  of  lime  is  gypsum,  or  plaster 
of  Paris.  Phosphate  of  lime  is  the  substance  which  forms  the 
bones  of  animals,  and  exists  in  the  mineral  apatite. 

Alumina  is  composed  of  27.4  parts  of  aluminium,  and 
24  parts  of  oxygen.  Its  composition  is  thus  represented. 
Al'^03  51.4.  It  is  an  inodorous,  tasteless  substance,  insoluble  in 
water,  possessing  the  properties,  both  of  an  acid,  and  of  an  alkali. 
When  moistened,  it  forms  a  ductile  mass,  and,  when  combined 
with  silicic  acid,  forms  clay.  It  is  the  base  of  all  kinds  of  pot- 
tery. 

Oxides  of  iron.  There  are  at  least  two  oxides  of  iron.  The 
protoxide  is  composed  of  twenty-eight  parts  of  iron  and  eight  of 
oxygen,  and  is  represented  by  FeO=36.  It  has  a  dark  blue 
color,  and  is  magnetic.  It  is  so  combustible  as  to  take  fire, 
sometimes,  in  the  open  air,  by  which  it  becomes  converted  in- 
to the 

Peroxide  of  iron  which  may  be  represented  by  Fe'^O^^BO. 
This  is  the  red  hemetite  of  mineralogists.  It  is  a  brownish- 
red  substance,  easily  thrown  down  from  a  solution  of  its  salts, 
by  ])ure  alkalies.  Both  of  the  oxides  combine  with  several 
acids,  and  form  a  numerous  class  of  salts.  The  sulphate 
of  the  protoxide  is  known  as  copperas.  The  carbonate  of  the 
X)rotoxide  exists  in  most  chalybeate  mineral  waters. 

Oxides  of  manganese.  There  are  several  oxides  of  manga- 
nese.    The  principal  one  is  the 

Peroxide  of  manganese,  which  is  composed  of  27.7  parts  of 
manganese  (Mn)  and  16  parts  of  oxygen.  The  symbol  is 
jMn02=43.7.  This  oxide  occurs  in  black  earthy  masses,  and 
is  not  affected  by  ex|)osure  to  the  air  or  water.  It  combines 
with  several  acids  and  forms  salts. 

Silicic  acid  is  composed  of  22.5  parts  of  silicon  and  24  parts 
of  oxygen  (Si03=46.5).  It  is  best  known  in  the  form  of  sand, 
rock-crystal,  quartz  and  flint.  It  is  a  tasteless,  very  infusible 
and  insoluble  substance;  and  although  it  is  not  acid  by  the  or- 
dinary chemical  tests,  it  is  the  most  powerful  of  acids,  forming 


168  BIOLOGY  OF  PLANTS. 

a  large  class  of  salts.  It  is  usual,  however,  to  call  the  com- 
pounds of  silicic  acid  with'bases,  silicates,  and  the  compounds  of 
other  acids  with  the  same  bases,  salts. 

Hydrochloric  acid  is  composed  of  one  equivalent  of  chlorine, 
35.42,    and  one  of    hydrogen,  1=36.42.    (HCl.)       This  acid,  in 
its  pure  state,  has  very  acrid  and  caustic  properties.     It  is  com- 
,         monly  called  muriatic  acid,  because  obtained  from  sea  salt.     Its 
^^i>>y"U)Jsprinciple^•  salt  is  hydrochlorate  of  anmionia,  known  as  sal  am- 
moniac. 

Sulphuric  acid,  a  compound  of  sixteen  parts  of  sulphur  and 
forty  of  oxygen,  is  an  oily  liquid  well  known  as  oil  of  vitriol. 

Phosphoric  acid  is  composed  of  two  equivalents  of  pliospho- 
rus,  31.4,  and  5  of  oxygen,  40=71.4  (symbol  P^QS).  This 
acid  resembles  snow  or  ice.  It  is  intensely  sour,  and  com- 
bines with  a  number  of  alkalies  and  alkaline  earths,  forming  a 
class  of  salts  called  phosphates.  Phosphate  of  lime  is  the  prin- 
cipal substance  in  the  bones  of  animals. 
.     JVitjic  acid  has  been  described,  p.  48. 

Is morphisnf  IS  a  term  used  to  designate  the  fact,  that  bodies  of 
very  different  chemical  constitution,  may  assume  the  same  crys- 
talline form,  and  may  displace  each  other  in  any  compound. 
When  this  is  the  case,  that  is,  when  one  body  is  substituted,  for 
another,  there  is  not  an  equal,  but  an  equivalent  proportion  ; 
thus,  when  soda  is  substituted  for  potassa,  thirty-one  parts  of 
the  former  take  the  place  of  forty-seven  of  the  latter. 


As  plants  uniformly  contain  several  inorganic  bodies,  we 
infer,  that  these  substances  are  necessary  for  the  formation  of* 
particular  organs.  For  although  the  inorganic  constituents 
of  plants  may  vary  according  to  the  soil  in  which  the  plant 
grows,  a  certain  number  of  them  is  absolutely  essential  to  its 
development.  The  principal  of  these  inorganic  substances 
are  potash,  soda,  magnesia,  lime,  alumina,  and  oxides  of  iron 
and  of  manganese,  which  are  the  inorganic  bases,  and  are 
generally  combined  with  silicic,  hydrochloric,  sulphuric,  phos- 
phoric, carbonic  and  nitric  acids. 

The  inorganic  bases  of  plants  vary  with  the  nature  of  the 
soil.  DeSaussure  and  Berthier  found  magnesia  in  the  ashes 
of  a  pine  tree,  growing  at  Mont  Breven,  but  none  in  the  ashes 


INORGANIC  CONSTITUENTS  OF  PLANTS.  169 

of  the  same  species  of  tree  from  Mont  La  Salle.  The  potash 
and  lime  also  varied  in  the  two  localities.  This  is  accounted 
for  by  the  fact,  that  one  inorganic  base  may  be  substituted 
for  another,  in  an  isomorplwus  proportion.  If,  therefore, 
there  is  not  in  a  soil  that  inorganic  base  which  the  plant  most 
likes,  it  will  take  up  a  quantity  of  some  other  base.  There 
is,  however,  some  inorganic  base,  which  a  species  of  plants 
prefers  to  any  other,  and  if  that  is  entirely  absent,  in  some 
cases  the  plant  will  be  imperfect  or  fail  to  grow  altogether, 
while  in  others  it  will  be  diminished  in  some  of  its  pro- 
ducts. As  these  bases  are  combined  with  inorganic,  and  al- 
so with  organic  acids,  and  as  it  is  only  with  the  latter  that 
substitutions  can  be  made,  when  one  base  is  substituted  for 
another,  a  different  quantity  will  be  employed,  because  one 
equivalent  of  base  must  be  substituted  to  saturate  the  acid, 
and  the  combining  ratios  differ  in  different  bases.  But  still 
there  is  a  remarkable  law  in  reference  to  the  quantity  o^inetal- 
lic  oxides  or  inorganic  bases  in  all  these  substitutions,  the 
quantity  of  oxygen  is  exactly  the  same ;  that  is,  there  is  an 
equal  number  of  equivalents  of  metallic  oxides,  whatever  sub- 
stitution may  be  made.  Hence,  if  the  soil  does  not  contain 
one  kind  of  base,  it  is  not  on  that  account  barren,  but  an- 
other may  supply  its  place.  But  notwithstanding  this  fact, 
some  bases  exert  a  better  injluence  upon  the  development 
of  plants  than  others.  For  example,  phosphate  of  magnesia, 
in  combination  with  ammonia,  is  found  invariably  in  the  seeds 
of  all  kinds  of  grasses.  It  is  contained  in  the  outer,  horny 
husk,  and  is  introduced  into  the  bread  with  the  flour,  although 
the  bran  contains  the  larger  quantity  of  it.  Hence,  this 
substance  is  necessary  to  the  perfect  development  of  the 
grasses  and  grains.  It  would  also  be  next  to  impossible  to 
raise  wheat  without  potash. 

There  are,  moreover,  certain  species  of  plants,  which  re- 
quire certain  alkalies  for  their  growth ;  such  as  the  sea-plants. 


170  BIOLOGY  OF  PLANTS. 

which  require  soda,  iodine,  or  some  substance  yielded  by  the 
sea,  as  common  salt.  Such  plants  will  follow  the  salt  water, 
wherever  it  is  found.  If  salt-works  are  opened  in  the  inte- 
rior of  a  country,  the  sea-weeds  will  find  the  spot,  and  mi- 
grate to  it. 

The  absolute  necessity  of  inorganic  bases  to  the  perfect 
development  of  plants,  is  shown  by  the  fact,  that  each  species 
of  plant  produces  organic  acids,  as  the  acetic,  tartaric,  ma- 
lic, etc.  These  acids  are  united  with  bases,  either  organic  or 
inorganic,  and  the  latter  is  the  case,  in  most  instances.  The 
quantity  of  these  acids  can  be  accurately  ascertained  in  each 
species  of  plant;  and  as  their  power  of  saturation  is  known, 
the  quantity  of  inorganic  bases  may  be  accurately  deduced. 
It  must  always  bear  an  exact  ratio  to  the  organic  acids.  The 
quantity  of  these  acids  varies  according  to  the  nature  of  the 
soil,  in  order  to  suit  the  different  organic  bases. 

As  the  roots  of  plants,  like  a  sponge,  imbibe  from  the 
soil  whatever  substances*  are  held  in  solution  by  water, 
it  is  evident,  that  many  of  the  inorganic  bases  and  other  mat- 
ters will  be  introduced  into  the  organs  of  the  plants,  which 
cannot  be  assimilated.  These  substances  are  again  returned 
to  the  soil.  This  process  has  been  inferred  from  observation. 
From  the  nature  of  the  case,  we  have  a  strong  presumption 
in  favor  of  its  truth.  It  may,  at  least,  explain  very  many 
phenomena  of  vegetation.  Macaire  Princep  has  shown  by 
experiment,  that  plants  made  to  vegetate  with  their  roots  in 
a  weak  solution  of  acetate  of  lead  (sugar  of  lead),  and  then 
in  rain-water,  yield  back  all  the  lead  absorbed.  So,  also, 
when  a  plant  is  sprinkled  with  nitrate  of  strontia,  it  will  ab- 
sorb it  by  the  leaves,  but  return  it  all  to.  the  soil ;  hence,  we 
may  color  a  plant  with  various  substances;!  but,   after   a 

*  The  roots  do  appear  to  possess  some  power  of  discriRiination,  as 

they  will  imbibe  different  quantities  of  substances  which  are  presented. 

t  "  When  the  soil,  in  which  a  white  liyacinth  is  growing  in  a  state 


INORGANIC  CONSTITUENTS  OF  PLANTS.  171 

while,  the  coloring-matter  will  all  be  returned  to  the  soil. 
When,  therefore,  a  plant  has  not  a  sufficient  quantity  of  its 
appropriate  alkali,  it  will  take  up  some  other,  but  may  return 
it  to  the  soil,  when  that  alkali  is  supplied  ;  hence,  the  impor- 
tance of  supplying  the  appropriate  alkalies  and  alkaline  earths, 
for  the  perfect  development  of  every  species  of  plants. 

The  source  of  the  inorganic  constituents  of  plants,  is  a 
point  much  more  easy  to  determine,  than  the  particular  form 
and  mode  of  their  introduction  into  the  organs  of  plants,  and 
of  their  assimilation. 

1.  Pgtassa.  Whence  do  plants  derive  their  potash? 
This  question  is  easily  answered.  The  rocks  contain  large 
quantities  of  potash,  locked  up  in  the  feldspar.  Granite  rocks, 
such  as  exist  abundantly  in  New  England,  contain  about 
seven  per  cent,  of  potash,  in  the  form  of  a  silicate,  that  is, 
united  with  silicic  acid.  This  potash  is  eliminated  by  the 
action  of  the  air,  and  by  carbonic  acid ;  but  growing  plants 
possess  the  power  of  decomposing  the  rocks,  and  of  obtaining 
it  in  much  larger  quantities.  This  is  proved  by  the  fact,  that 
plants  growing  in  a  glass  vessel,  will  decompose  the  glass,  to 
obtain  the  potash  which  enters  into  its  composition. 

The  quantity  of  potash  in  a  soil,  is  sufficient  to  sustain 
most  plants  for  an  indefinite  period  of  time.  We  might  al- 
most say,  that  it  is  inexhaustible  ;  for  pine  plain  soil 
of  six  inches  in  depth,  contains,  per  acre,  thirty-six  tons  of 
potash,  and  a  ton  and  a  half  of  lime.  Some  plants,  however, 
such  as  wheat  and  tobacco,  by  being  planted  upon  the  same 
soil  for  a  series  of  years,  will  exhaust  the  potash  to  such  an 
extent,  that  a  change  of  crops  must  be  resorted  to,  to  restore 
fertility.     There  may  be  some  cases,  in  which  minerals  be- 

of  blossom,  is  sprinkled  with  the  juice  of  the  Phytolaca  decandra 
(American  nightshade),  the  white  blossoms  assume,  in  one  or  two 
hours,  a  red  color,  which  again  disappears  after  a  few  days  under  the 
influence  of  sunshine,  and  they  become  vv^hite  and  colorless  as  be- 
fore,"— L. 


172  BIOLOGY  OF  PLANTS. 

come  wholly  decomposed ;  and,  when  that  is  the  case,  the  soil 
becomes  absolutely  barren,  and  nothing  can  restore  fertility 
but  the  addition  of  alkalies  and  gravel ;  hence  the  necessity 
and  utility  of  a  rotation  of  crops ;  for  when  all  the  potash  has 
been  removed  from  the  soil  by  one  family  of  plants,  other 
plants  may  be  substituted,  which  do  not  require  this  alkali  for 
their  growth. 

In  other  cases,  jTree  alkali  is  needed.  Hence  the  effect  of 
ploughing  in  green  crops,  and  the  utility  of  fallows.  The 
growing  plant  eliminates  the  potash  from  the  feldspar,*  and 
it  is  then  turned  into  the  soil  and  is  ready  to  be  applied  to 
future  crops. 

All  kinds  of  grain  contain,  in  the  outer  part  of  their  leaves 
and  stalks,  a  large  quantity  of^  s'lViCRte  of  potash,  which  must 
be  derived  from  the  soil.  If  now  we  increase  the  amount  of 
grass  or  grain  by  means  of  gypsum,  a  larger  quantity  of  potash 
will  be  eliminated,  and  the  free  alkali  will  be  carried  off,  so 
that  in  a  short  time,  the  crop  will  be  diminished,  and  either 
a  fallow  or  some  other  means  must  be  resorted  to,  to  restore 
that  alkali. 

The  planters  of  Virginia,  according  to  Liebig,  exhausted 
their  soils  by  cultivating  for  a  century  in  succession,  tobacco 
and  wheat  on  the  same  land  without  manure.  By  this  pro- 
cess, twelve  hundred  pounds  of  alkalies  were  in  the  course 
of  one  hundred  years,  abstracted  from  every  acre  of  soil. 
Thus  these  lands  were  nearly  deprived  of  alkali,  and  are 
now  barren  wastes.     Hence  the  necessity  of  returning  the 

*  There  is  not  much  danger  that  the  alkali  will  be  exhausted  by 
this  process.  The  quantity  contained  in  the  rocks,  is  almost  inex- 
haustible, compared  with  that  taken  up  by  plants ;  for  it  is  found, 
that  the  wheat  straw,  grown  on  an  acre,  takes  up  only  twenty-two 
pounds  of  potash,  and  the  quantity  in  the  soil  would  be  sufficient  for 
the  straw,  during  a  period  of  three  thousand  years.  The  quantity  of 
potash  on  ap  acre  of  granitic  rock  six  inches  in  depth  varies  from 
ninety  to  one  hundred  and  twenty  tons,  but  a  fsir  less  quantity  is 
found  in  the  same  depth  of  soil. 


SOURCE  OF  SODA.  173 

potash  to  the  soil,  in  the  vegetable,  animal  and  saline  ma- 
nures. If  no  vegetable  and  animal  matters  are  added,  a 
constant  course  of  cropping  will  extract  the  free  alkalies, 
and  however  rich  the  soil  may  be  in  humus,  plants  will  not 
flourish. 

The  form  in  which  potash  enters  the  organs  of  plants, 
and  the  mode  of  assimilation,  is  a  matter  of  theory.  It  ex- 
ists in  the  form  of  a  silicate,  in  ashes,  in  feldspar  and  in 
manures.  It  is  possible  that  it  is  dissolved  in  water  and  thus 
conveyed  to  the  roots  of  plants.  It  is  also  found  in  com- 
bination with  organic  acids.  If  it  were  introduced  then,  in 
the  form  of  an  oxide  dissolved  in  water,  it  would  combine 
with  the  organic  acids  in  the  plant,  and  form  the  vegetable 
compounds  in  which  it  is  found.  It  may  be  introduced  in 
combination  with  humic,  crenic  and  apocrenic  acids.  But 
the  most  probable  theory  is,  that  potash  is  combined  with 
nitric,  or  some  of  the  inorganic  acids,  and  introduced  as  a 
salt ;  that  it  is  decomposed  by  the  organic  acids  in  the  plant, 
and  the  acid,  either  sent  out  to  act  upon  the  silicates  and 
obtain  more  alkali,  or  decomposed  and  its  elements  assimi- 
lated. 

2.  Soda.  The  source  and  the  assimilation  of  soda  is  sim- 
ilar to  that  of  potash.  The  rocks  which  supply  soda  to 
plants  are  very  few.  It  is  obtained  from  the  sea  or  salt  wa- 
ter; hence,  plants  containing  this  alkali  in  the  greatest 
abundance,  are  found  near  the  sea  or  salt  springs.  Com- 
mon salt  is  a  chloride  of  sodium,  and  forms  soda  in  the  form 
ofhydrochlorate  of  soda  by  the  decomposition  of  the  salt  and 
the  water.  Now  a  small  quantity  of  salt  is  evaporated  from 
salt  water,*  is  carried  inland,  and  becomes  one  source  of 
the  soda  of  plants ;  hence  the  useful  effects  of  salt  upon  some 
soils,  and  for  particular  crops. 

3.  Magnesia.     Magnesia  is  also  derived  from  the  rocks, 

*  Liebig,  p.  192. 

15 


174  BIOLOGY  OF  PLANTS. 

and  is  much  more  abundant  than  soda.*  It  is  contained  in 
feldspar  and  mica,  two  ingredients  of  all  granitic  soils,  also 
in  hornblende,  but  especially  in  serpentine.  The  latter 
rock  contains  from  forty  to  forty- four  per  cent.  Hence  it 
is  an  ingredient  of  all  soils,  and  is  either  eliminated  by  the 
growing  plants,  or  by  the  acids  in  the  soil.  The  phosphate 
of  magnesia,  as  we  have  seen,  is  an  invariable  constituent  in 
all  kinds  of  grass.  This  alkali  may,  however,  be  extracted 
from  the  soil,  and  must  be  returned  by  animal  and  vegetable 
manures. 

Theory  of  assimilation.  Magnesia  may  enter  the  organs 
of  the  plant,  as  a  phosphate.  But  that  plants  should  assim- 
ilate bodies  just  as  they  are  receivpd  into  their  organs,  is 
contrary  to  the  general  doctrine.  It  unites  with  several 
acids  and  is  probably  introduced  in  several  forms.  In  the 
transformations  which  take  place,  the  phosphoric  acid  may 
be  formed,  and  combine  with  the  magnesia  in  the  act  of  as- 
similation. 

4.  Lime.  Lime  is  found  in  the  ashes  of  most  plants,  and 
is  derived  from  the  granitic  rocks,  and  from  the  carbonate 
and  sulphate  of  lime,  two  very  abundant  substances  in  na- 
ture. The  quantity  contained  in  the  soils  of  New  England 
is  very  small,  being  less  than  three  per  cent.  Hence,  lime  is 
added  to  most  soils  with  the  highest  benefit,  either  as  pi  aster  j 
marl  or  air-slacked  lime,  which  latter  has  become  partly  car- 
bonated. 

Theory  of  assimilation.  The  mode  by  which  this  is  in- 
troduced into  the  organs  of  plants,  is  probably  in  the  form  of 
geate,  or  crenatc  and  humatc  of  lime,f  a  substance  always 
found  in  the  humus  of  soils. 

*  Granitic  rocks  contain  from  one  to  three  per  cent. }  an  acre  six 
inches  deep  would  yield  from  ten  to  eighty  tons. 

t  If  too  much  lime  is  added,  it  may  form  a  super-salt,  iess  soluble 
an  the  other,  and  hence  the  liability  of  injuring  a  soil  by  its  appli- 
cation.    A  small  quantity  only  is  required  for  the  growth  of  plants. 


SOURCE  OF  SILICA.  175 

Some  plants  contain  sulphate  of  lime  or  gypsum,  as 
clover,  while  in  others,  the  lime  is  found  as  a  tartrate  or 
malate,  that  is,  in  combination  with  organic  acids,  which  lat- 
ter must  have  been  formed  before  the  lime  could  be  assimi- 
lated. 

Phosphate  of  lime  is  a  powerful  manure,  and  may,  in 
small  quantities,  enter  the  organs  of  plants.  But  in  this 
case,  as  in  that  of  potash,  the  great  point  is  to  furnish  it  in 
any  form. 

5.  Alumina  is  sometimes  found  in  plants,  but  in  very 
small  quantities.  It  may  enter  in  combination  with  phos- 
phoric acid,  or  with  crenic  and  apocrenic  acids. 

6.  Silica  or  silicic  acid.  The  epidermis,  or  outer  bark 
of  trees,  the  vessels  in  which  the  sap  circulates,  and  the  sur- 
face of  the  grains  and  grasses,  are  composed  in  part  of  this 
acid.  As  it  is  not  soluble  in  water,  nor  in  cold  alkalies,  the 
most  common  solvents  in  the  soil,  it  has  been  a  point  of 
some  difficulty,  to  determine  the  form  in  which  it  can  be  in- 
troduced. 

It  is  supposed  by  some,  that  it  is  combined  with  crenic 
acid,  a  compound  which  is  found  in  river  water,  and  in  the 
soil.  This  substance  must  enter  the  roots  of  plants  with 
water,  and  may  then  be  assimilated. 

It  is  possible,  however,  that  the  silica,  found  in  plants,  is 
introduced  by  means  of  galvanic  action,  or  the  catalytic  force 
of  life. 

There  is  still  another  mode  of  introducing  this  substance. 
It  forms  soluble  salts  with  alkali,  as  potash,  and  when  first 
liberated  from  its  combinations,  according  to  a  well  known 
law,  the  silica  becomes  soluble,  and  capable  of  entering  the 
organs  of  plants. 

7.  The  metallic  oxides  of  iron  and  manganese  are  found 
in  some  plants,  and  are  derived  from  the  soil.     Iron  is  the 

One  grain  of  lime,  in  a  hundred  of  the  soil,  will  produce  fertility, 
Avhere  all  v/as  barren  before. 


176  BIOLOGY  OF  PLANTS. 

most  widely  diffused  substance  in  nature,  nearly  all  rocks 
containing  traces  of  it.     Iron  is  found  in  many  seeds. 

Manganese  is  nearly  as  widely  disseminated,  but  is  found 
in  still  less  quantities,  both  in  the  soil  and  in  the  organs  of 
plants. 

8.  Phosphoric  acid  has  been  found  in  all  plants  hitherto 
examined,  and  always  in  combination  with  alkalies  and  alka- 
line earths.  The  seeds  of  different  grains  form  a  large  quan- 
tity of  phosphate  of  magnesia.  This  acid  is  derived  from 
the  soil,  and  is  an  ingredient  in  all  lands  capable  of  cultiva- 
tion. Phosphoric  acid  has  also  been  detected  in  all  mineral 
waters.  Sulphuret  of  lead  (galena)  contains  crystallized 
phosphate  of  lead.  Phosphate  of  alumina  often  encrusts  rock 
crystals.  Phosphate  of  lime  is  found  in  many  rocks,  and 
even  in  volcanic  holders.  There  can  be  no  doubt  but  that 
this  acid  is  developed  in  the  soil,  and  supplies  phosphate  of 
lime  to  plants,  and  plants  furnish  it  to  the  bones  and  brains 
of  animals. 

9.  Sulphuric,  nitric  and  carbonic  acids,  combined  with 
potash  and  other  alkalies,  and  common  salt,  or  chloride  of 
sodium,  are  found  in  some  plants. 

Nitrate  of  potash  is  formed  during  the  fermentation  of  ma- 
nures. Sulphuric  acid  is  formed  from  the  sulphuret  of  iron 
which  is  found  in  most  rocks. 

Common  salt,  (chloride  of  sodium,)  must  come  from  the 
sea,  or  from  animal  manures,  as  it  could  not  be  retained  in 
the  soil,  owing  to  its  solubility.  Very  small  quantities  of  ox- 
ide of  copper,  and  some  metallic  fluorides  are  absorbed  by 
some  plants,  although  we  cannot  afhrm,  that  they  are  ne- 
cessary to  their  growth. 

10.  Some  plants  also  take  up  small  quantities  of  iodine 
and  bromine  in  the  form  of  iodides  and  bromides ;  but  wheth- 
er they  are  necessary  to  the  growth,  cannot  be  fully  ascer- 
tained, although  it  is  probable  they  are,  since  such  plants  are 
never  found  away  from  the  sea,  the  source  of  these  sub- 


INORGANIC  CONSTITUENTS.  177 

Stances.  Sea  plants  seem  to  be  collectors  of  iodine  and  bro- 
mine, just  as  land  plants  are  of  alkalies,  such  as  potash,  etc. 

We  do  not  know  in  what  form  all  of  these  inorganic  con- 
stituents of  plants  enter  the  organs,  nor  the  changes  that 
are  wrought  upon  them  in  the  process  of  assimilation  ;  but 
we  may  derive  from  the  doctrine  of  transformations  already 
described,  the  general  nature  of  the  process,  and  the  best 
idea  we  can  obtain  of  nutrition  and  assimilation. 

Thus  it  appears,  that  the  inorganic  constituents  of  plants 
are  as  indispensable  to  their  perfect  development,  as  the  car- 
bon, oxygen,  hydrogen  and  nitrogen.  It  is  therefore  of  the 
first  necessity,  that  these  substances  should  be  supplied  to 
plants  in  their  proper  proportion.  The  facts  developed  in 
this  section,  relative  to  the  source  of  the  constituents  of 
plants,  illustrates  the  need  there  is  of  proper  attention  to  the 
soil,  as  it  is  from  the  soils  that  most  of  the  ingredients,  ne- 
cessary to  their  perfect  growth  are  derived. 

Having  now  considered  the  general  conditions  requisite  to 
the  life  of  veoretables,  with  the  various  changes  which  take 
place  in  the  phenomena  of  vegetation,  we  will  here  close  the 
subject  of  Biology  ;  not  because  we  have  exhausted  it,  but 
because  enough  has  been  advanced,  to  give  the  reader  a  gen- 
eral idea  of  the  vegetable  processes,  and  of  the  utility  of  sup- 
plying the  proper  conditions,  for  the  life  and  growth  of  those 
vegetable  substances,  which  are  the  support  of  the  animal 
kingdom.  Any  means,  which  shall  increase  these  products, 
are  to  be  sought  out  with  the  most  diligent  care  ;  we  have, 
therefore,  devoted  a  large  portion  of  succeeding  chapters  to 
the  subject  of  the  soils,  as  the  most  direct  means  of  secur- 
incr  so  desirable  an  end. 


15* 


GEOLOGY  AND  CHEMISTRY  OF  SOILS. 


CHAPTER  IV. 

ROCKS  AND  THEIR  RELATIONS  TO  VEGETATION. 

Soil  is  formed  by  the  decomposition  and  wearing  down  of 
ihe  rocks,  which  are  mingled  with  variable  quantities  of  ani- 
mal and  vegetable  matters.  All  soils  consist  of  compound 
bodies,  and  these  compounds  are  generally  formed,  by  the 
union  of  two  or  three  simple  substances.  In  order,  therefore, 
to  understand  the  nature  of  soil,  and  its  relations  to  vegeta- 
tion, it  will  be  necessary  to  give  a  general  view  of  the  simple 
and  compound  bodies,  which  enter  into  the  composition  of 
the  rocks,  the  manner  in  which  they  are  combined,  and  the 
process  by  which  the  rocks  are  converted  into  soil. 

Sect.  1.  Simple  Bodies  which  enter  into  the  Composition  of 
the  Rocks. 

The  number  of  simple  bodies  known  to  chemists,  is  fifty- 
five.  Of  these,  only  fourteen  enter  into  the  composition  of 
rocks  and  soils  ;  hence,  these  fourteen  bodies  constitute 
nearly  the  whole  matter  of  the  globe.  The  remaining  sub- 
stances are  found  either  in  too  small  quantities  to  affect  the 
general  mass,  or  exist  only  in  particular  locations  of  limited 
extent. 

The  proportion  in  which  these  bodies  exist  in  the  rocks, 
beginning  with  the  most  abundant,  is  nearly  in  the  following 


METALS.  179 

order  ;  oxygen,  silicon,  calcium,  aluminium,  potassium,  iron, 
hydrogen,  sodium,  magnesium,  manganese,  carbon,  sulphur, 
phosphorus  and  nitrogen. 

Some  of  these  substances,  with  their  combinations,  have 
been  described  in  previous  chapters.  It  is  intended  here,  to 
arrange  them  into  their  natural  groups,  and  to  give  a  general 
description  of  those  which  have  not  yet  been  referred  to. 

I.  Seven  of  these  simple  bodies  already  described,  viz. 
oxygen,  hydrogen,  carbon,  nitrogen,  sulphur,  silicon  and  phos- 
phorus, are  non-metallic  substances.  With  the  exception  of 
oxygen  and  nitrogen,  they  are  combustible,  and  with  the  excep- 
tion of  carbon,  do  not  exist  in  the  rocks  in  their  pure  state. 

II.  The  remaining  substances  are  Metals.  These  are  di- 
vided into  three  groups.  1.  Potassium  and  sodium,  which 
are  metallic  bases  of  the  alkalies  potassa  and  soda.  2.  Alu- 
minium, calcium  and  magnesium,  which  are  the  metallic 
bases  of  the  alkaline  earths  alumina,  lime  and  magnesia.  3. 
Iron  and  manganese,  which  are  the  bases  of  metallic  oxides. 

Potassium  is  a  white  metal,  lighter  than  water,  and  so  soft, 
that  it  easily  yields  to  the  pressure  of  the  fingers.  It  is  the 
most  combustible  of  the  simple  substances.  This  is  owing 
to  its  affinity  for  oxygen,  which  it  will  abstract  from  water 
with  such  rapidity,  as  to  burn  upon  its  surface  with  a  beauti- 
ful purple  flame.  It  thus  decomposes  the  water,  and  forms 
the  alkali  potassa,  which  is  the  basis  of  potash.  It  is  widely 
disseminated  in  the  rocks,  though  not  in  very  large  quanti- 
ties. 

Sodium  is  also  a  white  metal,  like  silver,  lighter  also  than 
water,  but  a  little  heavier  than  potassium,  to  which  it  is  simi- 
lar in  texture  and  consistency.  It  is  less  combustible  than 
potassium,  but  will  also  rapidly  decompose  water  to  obtain 
its  oxygen,  with  which  it  forms  the  pure  alkali  soda,  the  ba- 
sis of  all  the  compounds  of  soda,  known  under  the  names  of 
common  salt,  glauber's  salts,  etc. 

Magnesium  is  a  pure  white  metal  resembling  silver,  very 


180  GEOLOGY  AND  CHEMISTRY  OF  SOILS. 

malleable,  and  fusible  at  a  red  heat.  It  combines  with  oxy- 
gen and  forms  magnesia,  which  possesses  alkaline  properties, 
and  is  the  basis  of  the  common  magnesia  (the  carbonate)  and 
epsom  salts.     It  exists  in  serpentine  rocks. 

Aluminium  is  a  grey  powder,  slightly  cohesive.  It  gen- 
erally exists  in  small  scales  or  spangles  of  a  metallic  lustre. 
When  combined  with  oxygen,  it  forms  alumina  the  basis  of 
all  clays,  and  is  a:  constituent  of  most  rocks,  especially  of  the 
primitive  and  tertiary  formations. 

Calcium  is  a  white  metal,  and  combines  with  oxygen  and 
forms  lime,  the  basis  of  all  lime  rocks,  shells,  marble,  chalk, 
plaster  of  Paris,  etc. 

Iron  is  a  well  known  metal,  existing  in  all  the  primitive 
rocks,  in  combination  with  oxygen  and  sulphur. 

Manganese  is  a  more  rare  metal,  of  a  greyish-white  color, 
existing  in  primitive  rocks  in  combination  with  oxygen,  and 
is  called  oxide  of  manganese,  or  peroxide  of  manganese. 

Chlorine,  iodine  and  hromine  are  found  in  sea-weeds  ;  jlu- 
orine  and  lithium  exist  in  some  plants,  but  in  small  quantities. 

Sect.  2.  Compounds  formed  hy  the  fourteen  simple  Bodies. 

I.  Primary  compounds,  or  bodies  composed  of  two  simple 
substances. 

The  combinations  of  these  fourteen  simple  substances, 
above  described,  form  three  distinct  classes  of  primary  com- 
pounds. 1.  Acids.  2.  Alkalies,  or  alkaline  earths  and  me- 
tallic oxides.     3.  Urets. 

1.  Acids.  Of  this  class,  only  five  or  six  enter  into  the 
composition  of  rocks;  viz.  silicic,  carbonic,  sulphuric,  phos- 
phoric, nitric  and  hydrochloric  or  muriatic  acids.  These 
acids  have  been  described  pp.  48, 168.  The  silicic  is  most 
abundant  in  the  rocks,  constituting  about  forty  per  cent,  of 
the  crust  of  the  globe.  Carbonic  acid  ranks  next  in  quan- 
tity.    Then  follow  the  others,  in   the  order  above  named. 


ALKALIES,  URETS,  SALTS,  SILICATES,  181 

The  most  important  property  of  acids  is  their  constant  de- 
sire to  unite  with  alkalies,  alkaline  earths  and  oxides;  and 
as  they  possess  different  degrees  of  affinity  for  bases,  they 
are  in  the  soil  constantly  exchanging  them. 

2.  Alkalies,  alkaline  earths  and  metallic  oxides.  The  al- 
kalies are  potassa,  soda  and  ammonia.  The  alkaline  earths 
are  lime,  magnesia  and  alumina.  The  oxides  are  oxides  of 
iron  and  of  manganese.  These  with  the  exception  of  the 
two  last,  do  not  exist  in  the  rocks  in  their  pure  state,  but  their 
agency  in  the  soil  is  of  the  highest  practical  interest  to  the 
farmer. 

3.  Urets.  The  urets  are  bi-elementary  compounds,  neither 
acid  nor  alkaline.  They  are  formed  by  the  union  of  the  non- 
metallic  combustibles  with  each  other  and  with  metals.  The 
principal  are  sulphuret  of  iron,  (iron  pyrites),  phosphuret  of 
iron,  carburet  ofiron,  phosphuret  of  lime,  phosphuret  of  sili- 
con, etc. 

Their  distinguishing  property  is,  a  readiness  to  change  into 
salts  through  the  influence  of  atmospherical  or  other  agents. 

II.  Secondary  compounds  or  scdts.  These  are  compounds 
formed  by  the  union  of  the  primary  compounds.  The  acids 
combine  with  the  alkalies,  alkaline  earths  and  oxides,  which 
are  called,  in  reference  to  the  acids,  bases,  and  form  ternary 
or  quaternary  compounds. 

Salts  may  be  conveniently  classed  under  their  respective 
acids. 

1.  Silicates.  The  silicates  are  those  compounds  or  salts, 
in  which  silicic  acid  combines  with  the  bases  above  named. 
Those  entering  into  the  composition  of  the  rocks,  are  the 
following :  silicates  of  potassa,  soda,  lime,  magnesia,  alumina, 
oxide  ofiron  and  of  manganese.  Almost  the  entire  mass  of 
rocks  is  composed  of  these  silicates,  and  from  seventy  to 
eighty  per  cent,  of  soils.  These  salts  when  neutral,  are  not 
soluble  in  water,  and  therefore  are  not  capable  of  being  dis- 
solved in  that  fluid,  except  in  very  minute  quantities ;  hence. 


182  GEOLOGY  AND  CHEMISTRY  OF  SOILS. 

they  remain  unaffected,  unless  substances  are  presented  capa- 
ble of  decomposing  them,  and  of  forming  soluble  compounds. 

2.  Carbonates  are  a  class  of  compounds  formed  by  the 
union  of  carbonic  acid  with  the  bases  above  mentioned.  All, 
excepting  the  carbonate  of  lime,  or  marble,  are  found  in 
small  quantities  in  the  rocks. 

Carbonate  of  lime  is  very  abundant,  forming  nearly  ^  part 
of  the  crust  of  the  globe. 

Carbonate  of  potassa  is  the  common  potash,  pearlash,  etc. 
and  is  usually  obtained  from  ashes. 

Carbonate  of  soda  is  the  well  known  substance  used  for 
soda  powders. 

Carbonate  of  magnesia  is  a  white  powder  used  in  medi- 
cine,"under  the  name  of"  calcined  magnesia." 

Carbonate  of  iron  is  more  widely  diffused  among  the  rocks, 
but  the  quantity  is  small. 

Carbonate  of  ammonia  is  a  powerful  stimulant  to  animal 
and  vegetable  organs,  and  is  found  in  the  fermentation  of  ani- 
mal manures,  and  exists,  according  to  Liebig,  in  the  atmos- 
phere. It  is,  as  we  have  seen,  one  of  the  substances  from 
which  plants  derive  their  nitrogen.  All  the  carbonates  are 
easily  decomposed,  and  have  an  important  influence  on  vege- 
tation, especially  by  means  of  their  action  upon  the  silicates 
from  which  alkali  is  obtained  for  the  use  of  the  vegetable. 

3.  Sulphates.  The  sulphates  are  formed  by  the  union  of 
sulphuric  acid  with  potassa,  alumina,  soda,  magnesia,  am- 
monia, lime,  oxide  of  iron  and  of  manganese.  Most  of  the  sul- 
phates are  well  known  substances.  The  sulphate  of  potassa 
and  alumina  is  known  by  the  common  name,  alum.  Sul- 
phate of  soda  is  glauber's  salts;  of  magnesia,  epsom  salts  ;  of" 
lime,  plaster  of  Paris  ;  of  oxide  of  iron,  copperas,  etc.  The 
most  abundant  sulphate  is  that  of  lime  or  plaster,  which 
forms  extensive  mountain  ranges  and  is  widely  disseminated 
among  the  rocks. 

4.  Nitrates.     The  nitrates  are  compounds  of  nitric  acid 


SIMPLE  MINERALS.  183 

with  the  bases  above  named.  The  nitrate  of  potassa  is  the 
nitre  or  salt-petre  of  commerce.  The  other  nitrates  are  rare- 
ly found  in  the  rocks.  Nitrate  of  soda  is  next  to  nitre  in 
importance. 

5.  Phosphates.  In  these  compounds,  the  acid  is  the  phos- 
phoric, and  the  most  abundant  sahs  are  the  phosphates  of  lime, 
found  in  most  rocks ;  phosphates  of  iron,  soda,  potassa,  etc. 

6.  Muriates.  The  muriatic  acid  forms  but  few  com- 
pounds, which  exists  in  any  considerable  quantities  in  the 
rocks.  Common  salt,  when  dissolved  in  water,  has  been  re- 
garded as  a  muriate  of  soda.  It  is  found  in  sea  water,  and 
widely  diffused  in  certain  geological  formations,  (the  new  red 
sandstone,)  but  most  writers  regard  it  as  a  chloride  of  sodium, 
a  compound  of  chlorine  and  sodium. 

The  compound  bodies,  Vv'hich  have  been  enumerated,  are, 
with  the  exception  of  silicic  acid  and  carbonate,  sulphate 
and  phosphate  of  lime,  rarely  found  in  the  rocks  in  a  pure  or 
separate  state.  They  are  variously  combined,  and  form  the 
natural  substances,  called  the  simple  minerals  ;  and  the  sim- 
ple minerals,  united  mechanically,  and  not  chemically,  form 
the  rocks. 

In  order  to  understand  the  character  of  the  rocks  and  the 
soil,  it  will  be  necessary  to  describe  these  compounds,  as 
they  actually  exist  in  nature. 

Sect.  3.  Simple  Minerals  which  enter  into  the  composition 
of  the  Rocks. 

Of  the  three  or  four  hundred  species  of  simple  minerals, 
only  seven  or  eight  form  the  great  mass  of  the  rocky  strata  of 
the  globe.  These  are  quartz,  mica,  feldspar,  hornblende, 
talc,  serpentine,  calcareous  spar,  or  limestone  and  pyrites. 

1.  Quartz  is  nearly  pure  silicic  acid.  It  exists  under  a 
a  great  variety  of  forms,  and  presents  different  appearances. 
The    purest  variety  is  rock  crystal,  which  is  limpid  and 


184  GEOLOGY  AND  CHEMISTRY  OF  SOILS. 

transparent.  The  impure  varieties  contain  variable  quanti- 
ties of  iron,  alumina,  manganese  and  nickel.  These  varie- 
ties are  found  under  the  names  of  jasper,  flint,  chalcedony, 
rose-quartz,  horn-stone,  chrysoprase,  feruginous  quartz,  cor- 
nelian, agate,  amethyst,  etc.  The  prevailing  color  is  that  of 
water,  or  white.  There  are  various  shades  of  red,  yellow, 
green,  blue  and  brown.  It  is  so  hard  as  to  scratch  glass,  but 
is  not  scratched  in  turn.  Its  lustre  resembles  glass,  and  may 
be  known  by  not  being  acted  upon  by  any  acid,  excepting 
the  hydrofluoric. 

2.  Feldspar  differs  from  quartz  in  having  a  paler  white 
color,  and  lamella  or  granula  texture.  It  scratches  glass,  and 
is  scratched  by  glass  in  turn.  It  is  a  silicate  of  alumina,  and 
is  composed  of  silica,  64  parts  in  100,  alumina  20,  potash 
10  to  14,  and  traces  of  lime,  oxide  of  iron  and  water. 

3.  Mica.  This  mineral,  known  under  the  name  of  ising- 
glass,  exists  in  thin, shining  scales,  and  in  broad  tables  or  plates. 
It  is  of  various  colors.  It  is  transparent,  and  the  laminae 
are  thin,  very  flexible,  elastic  and  very  tough.  These  char- 
acters sufl^ciently  distinguish  it  in  the  rocks.  It  is  a  silicate^ 
and  varies  in  composition.  A  specimen  analyzed  by  Rose, 
gave 

0.^6 
0.56 
1.39 

A  specimen,  analyzed  by  Turner,  had  5.49  of  lithia, 
but  no  oxide  of  iron.  Its  composition  may  be  stated  gener- 
ally 


Silica 

47..50 

Oxide  of  manganese 

Alumina 

37.2 

Fluoric  acid 

Potash 

9.60 

Water 

Oxide  of  iron 

3.20 

Silica 

48 

Oxide  of  iron 

lto2 

Alumina 

34 

Oxide  of  manganese 

1  to  2 

Potash 

8  to  9 

It  appears,  therefore,  to  be  a  compound  of  the  silicate  of 
alumina,  potassa,  oxide  of  iron  and  of  manganese. 

4.  Talc  resembles  mica  in  its  thin,  shining  scales,  but 
may  be  distinguished  from  it  by  its  want  of  elasticity.      It  is 


Silica 

43.83 

Magnesia 

13.61 

Lime 

10.16 

Alumina 

7.47 

SIMPLE  MINERALS.  185 

softer,  yielding  easily  to  the  nail,  and  has  a  soapy  feel.  It 
includes  the  varieties,  chlorite  (which  is  green),  nacrite, 
green  earth,  steatite  or  soapstone,  and  vermiculite. 

It  is  composed  of  silica  62,  magnesia  27,  oxide  of  iron  3.5, 
alumina  1.5,  water  6.  Nacrite  and  green  earth  have  from  4 
to  17  per  cent,  of  potash,  and  a  trace  of  lime.  It  appears  to 
be  a  silicate  of  magnesia,  and  of  the  other  bases  which  are 
above  mentioned. 

Hornblende  is  a  black  or  brown  mineral,  exceedingly  tough, 
and. of  an  earthy  appearance  when  not  crystallized. 

It  is  composed,  according  to  the  analysis  of  Bornsdorf,  of 

Protoxide  of  iron  18.75 

Protoxide  of  manganese  1.15 

Hydrofluoric  acid  0.41 

Water  0.50 

Hence  it  is  a  silicate  of  magnesia,  lime,  oxide  of  iron,  etc. 

Serpentine.  Serpentine  is  a  hard  compact  mineral,  of  a 
resinous  or  greasy  lustre,  and  of  a  dark-green  or  blackish- 
green  color.  According  to  the  analysis  of  Shepherd,  it  is 
composed  of 

Silica  40.08  I  Water  15.67 

Magnesia  41.40  I  Protoxide  of  iron  2.70 

A  species  from  Lynnfield,  Mass.  analyzed  by  Dr.  C.  T.  Jack- 
son, gave  silica  37,  magnesia  42,  oxide  of  iron  2,  water  15. 
Hence,  serpentine  is  almost  wholly  a  silicate  of  magnesia. 

Calcareous  spar,  or  carbonate  of  lime,  is  well  known  by  the 
names  of  marble,  chalk,  limestone,  etc.  It  assumes  a  great 
variety  of  forms,  and  may  be  known  by  the  brisk  efferves- 
cence produced  by  dropping  on  to  it  a  few  drops  of  sulphuric 
acid.  It  is  composed,  according  to  Phillips,  of  carbonic  acid 
44,  lime  55.5.  Limestone  is  found,  in  great  abundance, 
but  it  is  not  always  pure.  It  often  contains  magnesia,  the  dolo- 
mite species  ;  iron ;  the  feruginous  limestone  ;  alumina ;  and 
silica.  The  limestones  of  Rhode  Island,  according  to  the 
analysis  of  C.  T.  Jackson,  contain  from  50  to  97.6  per  centi. 
16 


186  GEOLOGY  AXD  CHEMISTRY  OF  SOILS. 

of  carbonate  of  lime ;  from  1  to  40  per  cent,  of  insoluble  mat- 
ter, probably  silicate  of  alumina ;  in  some  cases,  4  per  cent, 
of  oxide  of  iron,  from  0.  to  40  per  cent,  of  magnesia.  The 
limestones  of  Massachusetts,  according  to  Prof  Hitchcock's 
analysis,  contain  from  44.8  to  99.6  per  cent,  of  carbonate  of 
lime ;  from  0  to  40  of  carbonate  of  magnesia  in  some  species ; 
from  0  to  8  per  cent,  of  carbonate  of  iron ;  and  from  0.4  to 
61.6  of  silicate  of  alumina.  The  sulphate  of  lime  or  plaster, 
with  the  phosphate,  may  also  be  included  in  this  group,  as  in 
some  cases  entering  into  the  composition  of  the  rocks. 

Pyrites,  or  iron  pyrites,  is  a  bisulphuret  of  iron,  and  exists 
extensively  in  primitive  rocks,  but  in  much  less  quantities 
than  the  preceding  minerals.  It  resembles  gold,  and  is  often 
taken  for  that  substance  ;  hence  it  has  been  called ybo/'s  gold. 

It  will  be  seen  that  silex  or  silicic  acid  is  the  most  abun- 
dant ingredient  in  those  simple  minerals  above  enumerated, 
and  alumina  the  next.  They  are  mostly  silicates  and  are  di- 
vided by  Dana  into  three  classes. 

1.  Silicate  of  alumina  and  potash  form  feldspar  and  mica. 

2.  Silicate  of  alumina  and  lime,  with  magnesia,  form  horn- 
blende. 

3.  Silicate  of  alumina  and  magnesia  form  serpentine  and 
talc,  and  silicic  acid  forms  quartz. 

Sect.  4.  Composition  of  the  Rocks. 
Rocks  are  composed  of  the  simple  minerals.  In  some  cases, 
the  minerals  may  be  seen  in  separate  portions,  united  me- 
chanically, as  in  granite.  In  other  cases  they  are  so  inter- 
mingled as  to  conceal  their  distinct  characters,  as  in  green- 
stone. Rocks  are  divided  by  geologists,  according  to  their 
supposed  origin,  into  two  separate  classes.  1.  Igneous 
rocks,  or  those  which  appear  to  have  been  fused  by  fire. 
2.  Aqueous  rock,  or  such  as  appear  to  have  been  deposited 
from  water,  or  which  have  resulted  from  the  decay  and  wear- 
ing down  of  the  first  class.     The  igneous  rocks  are  highly 


COMPOSITION  OF  THE  ROCKS.  .  187 

crystalline  in  their  structure  ;  such  as  granite,  sienite,  gneiss, 
greenstone,  porphyry,  basalt,  and  ancient  and  modern  lava. 
They  constitute  the  largest  portion  of  the  crust  of  the  globe. 
They  are  destitute  of  animal  or  vegetable  remains,  and  hence 
are  called  non-fossiliferous  rocks.  The  aqueous  rocks  in- 
clude the  various  deposits  of  clay,  sand,  gravel,  conglome- 
rates, sandstones,  slates,  etc.  They  are  composed,  essen- 
tially, of  the  ingredients''of  the  igneous  recks.  They  contain, 
with  the  exception  of  a  few  rocks  in  the  lower  part  of  the  se- 
ries, the  remains  of  animals  and  plants,  and  are  hence  called 
fossilifcrous  rocks. 

Rocks  are  subdivided  into  several  groups.  The  un- 
stratified  or  non-fossiliferous  rocks,  may  be  divided  chemically 
into  two.  The  highly  crystalline  varieties,  usually  called  pri^ 
mary,  such  as  granite,  gneiss,  mica  slate  and  porphyry,  form 
one  class,  and  the  trappcan  rocks,  such  as  greenstone,  basalt 
and  trap,  form  the  other  class.  The  difference  in  their  chem- 
ical constitution  is  this;  that  the  first  class  contain  about  20 
per  cent,  more  of  silex,  and  from- 3  to  7  per  cent,  tessof  lime, 
magnesia  and  iron  than  the  second  class; 

The  fossiliferous  rocks  are  very  various  in  composition,  al- 
though they  correspond  more  nearly  to  the  trappean  variety 
*'  in  containing  less  silica  and  more  lime,  magnesia  and  alu- 
mina." 

The  following  are  some  of  the  most  abundant  rocks, 
composed  of  the  simple  minerals. 

1.  Granite  is  composed  by  the  mechanical  union  of  quartz, 
feldspar  and  mica.  The  quartz  is  in  irregular  masses,  the 
feldspar  often  crystallized,  and  the  mica  in  thin  shining  scales. 
Hornblende  sometimes  displaces  mica  and  forms  what  has 
been  called  sienite. 

2.  Gneiss  is  similar  in  composition  to  granite,  but  appears 
to  be  formed  by  the  destruction  and  deposition  of  the  granite 
by  water. 

3.  3Iica  slate  is  formed  by  quartz  and  mica,  the  latter  pre- 


188  GEOLOGY  AND  CHEMISTRY  OF  SOILS. 

dominating  so  as  to  give  the  rock  a  slaty  and  shining  appear- 
ance. 

4.  The  argillaceous  slate  and  clay  slate  are  made  up  prin- 
cipally of  quartz  and  alumina,  or  argillite,  \thich  seems  to 
be  decomposed  feldspar,  containing  from  7  to  10  per  cent,  of 
potash. 

5.  Talcose  slates  consist  of  talc,  alumina  and  quartz. 

6.  Hornblende  rocks  and  hornblende  slate  are  composed 
mostly  of  hornblende. 

7.  Graywacke  is  formed  of  quartz,  clay  slate  and  lime. 

8.  The  trappean  rocks  have  a  similar  constitution. 

9.  Limestones  generally  contain  clay,  feldspar,  porphyry 
and  clay  slate,  although  there  are  extensive  beds  of  the  pure 
carbonate  of  lime. 

10.  The  various  sandstones  and  slates  are  composed  mostly 
of  silex  and  alumina,  and  hence  are  formed  of  the  minerals 
quartz  and  feldspar. 

Sect.  5.   Origin  of  Soils, 

Having  attended  to  the  manner  in  which  the  simple  bodies 
are  united  to  form  the  rocks,  the  way  is  now  prepared  to 
describe  the  process  by  which  the  rocks  are  converted  into 
soils. 

The  researches  of  modern  geologists  have  established  the 
fact,  that  all  soils  were  originally  formed  by  the  disintegra- 
tion, decomposition  and  wearing  away  of  rocks.  The  rock 
has  been  gradually  pulverized,  and  brought  into  the  condi- 
tion of  soil.  This  effect  has  been  produced  by  the  mechani- 
cal and  chemical  agency  of  air,  water,  living  and  decaying 
vegetables.     This  process  is  constantly  going  forward. 

1.  The  oxygen  of  the  atmosphere  combines  chemically  with 
the  metals  and  decomposable  minerals,  and,  by  forming  new 
compounds,  causes  them  to  crumble  down.  Water  also  im- 
parts its  oxygen,  and  produces  a  similar  effect.     The  surface 


AGENCY  OF  PYRITES  AND  WATER.  189 

of  rocks,  in  this  way  becomes  pulverized  to  a  greater  or  less 
depth.* 

The  principal  mineral  substances  with  which  the  oxygen 
of  the  air  and  of  water  unite,  are  iron,  manganese  and  pyrites. 

When  a  rock  contains  iron  or  manganese,  in  a  low  state 
of  oxidation,  these  oxides  attract  more  oxygen  from  the  air 
and  water,!  increase  in  bulk  and  split  or  cleave  into  their 
layers ;  thus  affording  an  opportunity  for  the  mechanical 
agency  of  water,  either  by  friction  or  by  freezing. 

2.  Pj/r/^es,  or  the  bi-sulphuret  of  iron,  exerts  the  most  pow- 
erful agency  in  the  decomposition  of  rocks,  and  perhaps  the 
most  extensive ;  as  this  mineral  is  widely  disseminated  through 
nearly  all  classes  of  rocks.  It  is  composed  of  sulphur  and 
iron.  The  sulphur  attracts  oxygen  from  the  air  and  from 
water,  and  forms  the  well  known  substance  sulphuric  acid 
(oil  of  vitriol).  The  iron  also  combines  with  oxygen  from  the 
same  source,  and  forms  an  oxide  of  iron.  The  acid  and  the 
oxide  now  unite  and  produce  a  new  compound,  the  sulphate 
of  iron  or  copperas,  a  substance  capable  of  being  dissolved  in 
water.  Thus  the  rock,  through  which  the  pyrites  is  dissemi- 
nated, is  crumbled,  thrown  or  changed  in  its  properties.  But 
the  action  does  not  stop  here.  The  sulphate  of  iron,  being 
dissolved  in  water,  which  is  constantly  penetrating  the  mass, 
is  brought  into  contact  with  feldspar,  and  both  are  decom- 
posed ;  the  sulphuric  acid  in  the  copperas  abandons  the  iron, 
and  unites  with  the  potash  and  lime  in  the  feldspar,  forming 
sulphate  of  potash  and  of  lime,  while  the  oxide  of  iron  is  de- 
posited in  the  form  of  iron  rust. 

*  This  process  is  called  disintegration,  and  some  examples  are 
found  in  Massachusetts,  where  the  gneiss  rocks  have  been  penetrated 
fifteen  feet.  The  rock  is  said  to  rot.  Almost  every  variety  of  rock  is 
constantly  undergoing  this  change. 

t  This  action  of  the  oxygen  of  the  air  and  of  water  to  produce  dis- 
integration, explains  the  effect  of  allowing  lands  to  remain  fallow,  by 
which  their  fertility  in  a  measure  is  restored 

16* 


190 


GEOLOGY  AND  CHEMISTRY  OF  THE  SOIL. 


When  the  pyrites  exists  m  slate  rocks,  containing  much 
alumina,  magnesia  and  lime,  the  sulphuric  acid  combines 
with  these  bases,  by  which  nearly  the  whole  rock  is  gradual- 
ly converted  into  soil.  Were  this  the  only  agent  acting  upon 
the  rocks,  the  character  of  the  soil  would  be  accurately 
known,  by  examining  the  rock  which  underlays  it ;  but  this  is 
rarely  the  case. 

3.  The  mechanical  agency  of  water,  aided  by  cold  and 
heat,  and  by  its  currents  and  waves,  not  only  aids  in  break- 
ing down  the  solid  masses,  but  transports  the  pulverized  ma- 
terials in  the  form  of  detritus,  and  deposits  them  in  lower 
lands.  Thus  the  substances  of  different  rocks  are  mingled 
together.  Freezing  water  exerts  an  immense  power  in  this 
respect.  The  water  penetrates  every  seam  and  crevice  of 
the  rocks,  and,  by  its  expansive  power  in  the  act  of  freezing, 
forces  the  parts  asunder,  and  creates  new  fissures,  which  are 
each  year  increased  in  number  and  width.  Nor  does  this 
influence  cease  after  the  rocks  are  fully  converted  into  soils ; 
each  year  the  expansive  force  of  water  tends  to  pulverize,  and 
render  the  earth  light  and  porous. 

The  friction  of  running  water  wears  off"  the  rocks,  and  re- 
moves that  which  has  become  broken  down  by  chemical  ac- 
tion. The  particles  being  suspended  are  carried  down  by 
the  force  of  the  stream,  and  deposited  along  the  banks  and  at 
the  mouths  of  rivers. 

That  the  agency  of  water,  at  some  ancient  period,  has  ex- 
erted a  very  great  influence  upon  the  rocks  and  soils  appears 
from  the  fact,  that  over  the  whole  northern  hemisphere,  the 
rocks  and  soils  have  nearly  all  been  removed  in  a  southerly 
direction,  and  the  materials  of  different  formations  variously 
mingled  together.  This  has  been  shown  to  have  resulted 
from  the  action  of  glaciers,  by  which  the  whole  surface  has 
become  scratched,  and  the  sand,  gravel  and  boulders  rolled 
up  into  hills,  with  ponds  and  vallies  between. 

4.  Decaying  plants  tend   to   convert  the  rocks  into  soils. 


AGENCY  OF  GROWING  PLANTS.  191 

The  vegetable  acids  are  capable  of  combining  with  the  lime, 
soda,  ammonia,  potash,  magnesia,  oxide  of  iron  and  manga- 
nese. These  bases  are  thus  withdrawn  from  the  rocks,  and 
the  latter  crumble  to  pieces,  and  salts  are  formed,  which  are 
useful  in  the  ^^nourishment  of  future  generations  of  plants. 
During  decay,  large  quantities  of  carbonic  acid  are  formed. 
This  acid  is  not  only  direct  food  for  plants,  but  is  capable  of 
combining  with  the  potash  in  the  feldspar  of  granitic  rocks, 
and  of  facilitating  their  decomposition.  This  acid  is  the 
most  powerful  agent  in  its  action  upon  the  alkalies,  even  de- 
composing the  silicates  and  forming  soluble  salts. 

5.  Groicing  plants  exert  the  most  powerful  agency  in  de- 
composing the  rocks.  Not  only  do  the  lichens,  mosses  and 
other  plants  insert  their  roots  into  the  crevices  of  the  rocks, 
and  by  keeping  them  moist,  favor  the  chemical  action  of  air 
and  water,  but  the  living  plant  forms  with  the  rock  or  soil  a 
galvanic  battery,  of  immense  power ;  by  this  means  the 
plant  is  enabled  to  obtain  from  the  soil  those  ingredients 
which  its  wants  may  require.  This  is  proved  by  the  fact, 
that  plants,  growing  in  glass  vessels,  will  decompose  the  glass 
to  obtain  the  potash,  of  which  the  glass  is  in  part  composed. 
It  is  highly  probable,  that  a  greater  amount  of  decomposition 
is  produced  in  this  way  than  by  all  other  causes  together. 
Similar  to  this  influence,  if  not  identical  with  it,  is  what  has 
been  called  "  catalysis  of  life ^  The  living  plant  acts  by  its 
presence  to  decompose  the  rocks,  and  to  effect  rapid  changes, 
which  not  only  convert  them  into  the  state  of  soil,  but  form 
the  elements  into  different  substances. 

The  above  process  will  serve  to  illustrate  the  chemical  and 
mechanical  agencies  which  are  constantly  at  work  tq  crumble 
down  the  solid  rocks,  and  bring  them  into  a  state  fit  for  the 
support  of  the  vegetable  kingdom.  These  agents  are  con- 
stantly active.  The  great  effect  of  stirring  the  soil,  is  to  fa- 
cilitate the  decomposition  of  the  rocks,  and  of  the  vegetable 
bodies  which   are  always  present   in  the  soil.     But  for  this 


192  GEOLOGY  AND  CHEMISTRY  OF  SOILS. 

agency,  the  soils  in  a  few  years  would  become  exhausted  of 
all  their  alkalies,  the  vegetable  matter  would  not  decay,  and 
hence  no  food  in  the  soil  would  be  provided  for  the  plant. 
Absolute  barrenness  must  therefore  succeed.  For  without 
alkalies  or  alkaline  earths  and  geine,  no  plants  can  grow. 

Depth  of  soil.  The  influence  of  the  agents  above  de- 
scribed, has  not  extended  to  an  average  depth  of  more  than 
15  feet ;  although  in  some  places,  the  soil  is  actually  more 
than  a  hundred  feet  in  depth.  This  is  but  a  small  por- 
tion of  the  whole  mass  of  the  earth,  whose  mean  diameter  is 
7,911  miles;  hence  "the  soil  would  be  less  in  proportion  to 
the  whole  earth,  than  the  slightest  tarnish  of  rust  on  an  iron 
globe  100  feet  in  diameter  compared  with  its  mass."  But  a 
small  part  of  this  constitutes  what  is  properly  denominated 
the  soil.  That  part  only  of  the  surface,  varying  from  3  to  20 
inches  in  depth,  which  has  become  mingled  with  vegetable 
and  animal  matters,  constitutes  the  true  soil,  and  it  is  most- 
ly this  part,  which  concerns  the  farmer,  and  which  is  pre- 
sented for  our  investigation,  classification,  description  and 
improvement. 


CHAPTER  V. 

SOILS  AND  THEIR  RELATIONS  TO  VEGETATION.  THEIR  ANAL- 
YSIS, COMPOSITION,  MUTUAL  ACTION  OF  THEIR  ELEMENTS, 
GEOLOGICAL  AND  CHEMICAL  CLASSIFICATION  AND  DESCRIP- 
TION. 

The  relation,  which  the  soil  sustains  to  vegetation,  has 
been  pointed  out  in  a  general  way  in  the  first  chapter,  p.  81, 
where  it  was  shown  to  be  one  of  the  essential  conditions  to 
the  action  of  the  vital  power  in  those  vegetables  which  were 
cultivated  for  the  use  of  man ;  furnishing  support  for  the  roots, 


ANALYSIS  OF  SOILS.  193 

a  medium  for  the  circulation  of  water,  and  for  those  chemical 
and  electrical  changes  which  must  take  place,  before  the  nu- 
triment could  be  prepared  and  introduced  into  the  vegetable 
organs ;  and  yielding,  by  its  salts  and  mineral  ingredients, 
both  food  and  stimulus  to  growing  plants.  It  was  remarked, 
however,  that  all  soils  did  not  perform  these  offices  with  the 
same  degree  of  fidelity,  but  a  few  were  fitted,  without  artifi- 
cial appliances,  to  facilitate  the  vigorous  action  of  the  vital 
principle,  and  the  perfect  development  of  all  the  vegetable 
organs. 

We  propose  now  to  consider  the  soil  as  a  specific  subject 
of  investigation,  to  give  the  modes  of  its  analysis,  to  point  out 
its  chemical  and  geological  character,  and  the  relation  of  each 
variety  to  the  cultivated  crops.  By  this  method,  the  intelli- 
gent agriculturist  may  learn  the  nature  of  his  soils,  the  gene- 
ral mode  of  improvement,  and  howto  adapt  his  crops  to  such 
as  are  fitted  by  nature  or  art  to  yield  the  most  bountiful  crops. 

Sect.  1.  Analysis  of  soils. 

The  importance  of  a  correct  knowledge  of  the  constitu- 
ents of  any  soil,  appears  from  the  fact,  that  without  it,  all  ex- 
periments must  be  conducted  in  the  dark. 

A  w^ant  of  such  knowledge,  has  given  rise  to  the  various 
discrepant  views  of  farmers,  relative  to  the  application  of  cer- 
tain salts  of  lime.  Experiments  are  tried  by  one  farmer,  and 
he  is  successful;  another  applies  the  same  substance  and 
fails ;  hence  we  have  the  most  contradictory  accounts  of 
nearly  every  mode  of  improvement,  and  the  consequence  is 
that,  though  there  are  constant  improvements,  in  individu- 
al cases,  no  generalization  can  be  made  applicable  to  every 
kind  of  soil.  An  analysis  of  a  soil  will  indicate  at  once  the 
mode  of  treatment.  There  can  be  no  doubt  here,  as  the  most 
fertile  soils  of  our  own  and  of  other  countries,  have  already 
been  analyzed,  and  their  composition  accurately  ascertained. 

Any  farmer,  then,  who  can  analyze  his  soil  himself,  or  pro- 


194  GEOLOGY  AND  CHEMISTRY  OF  SOILS. 

cure  it  done  by  some  scientific  chemist,  may  compare  its 
composition  with  that  of  fertile  soils,  and  the  exact  mode  of 
improvement  will  be  seen  at  a  single  glance.  This  excludes 
all  empyricism,  all  hap-hazard  experiment,  all  unnecessary  ex- 
pense,* and,  for  a  trifling  sum,  will  ensure  complete  success. 
The  grand  desideratum,  in  this,  as  well  as  in  every  other 
art,  is  the  the  union  of  thcorij  and  practice.  Agriculture 
should  not  be  pursued  as  a  mere  art,  a  routine  of  mechani- 
cal drudgery,  but  the  scientific  principles  upon  which  the 
success  of  the  art  must  ultimately  depend,  should  be  thor- 
oughly understood  by  every  farmer. 

Why  should  the  agricultural  community  be  the  only  class 
who  are  not  educated  in  the  science  of  their  profession  ? 
Why  should  they  suffer  their  art,  the  first  and  the  most  im- 
portant of  all  others,  to  rank  lowest  in  the  scale  ?t 

It  is  not  expected,  that  every  farmer  will  have  a  labora- 
tory, furnished  with  all  the  materials  necessary  to  a  complete 
and  accurate  analysis  of  his  soils.  This  must  be  left  to  a 
few  practical  chemists,  but  the  rising  generation  of  farmers, 
may  very  easily  obtain  such  knowledge,  as  will  enable  them 

*  For  the  trifling  sum  of  ten,  or  at  most,  twenty  dollars,  almost  any 
farmer  can  ascertain  the  composition  of  any  of  his  fields,  and  have  the 
mode  of  improvement  pointed  out.  This,  without  doubt,  would  be 
more  than  returned  to  him  in  a  single  season,  and  would  be  increas- 
ed in  tenfold  proportion  in  succeeding  years.  Were  half  the  time 
and  money,  which  have  been  wasted  in  useless  experiments,  without 
any  scientific  principles  to  gnide,  expended  for  the  purpose  of  analy- 
sis, our  farmers  would,  long  ere  this,  have  had  the  satisfaction  of  see- 
ing their  farms  gradually,  but  surely,  arriving  to  a  state  of  fertility, 
of  which  they  had  never  dreamed ;  and  instead  of  going  West  to  seek 
more  fertile  lands,  would  actually  be  able  to  compete  with  the  West- 
ern farmer  in  any  market  under  lieaven. 

t  If,  with  the  rapidity  of  improvement  among  every  other  class, 
our  farmers  do  not  take  care  of  their  interests,  by  improving  their 
minds  and  studying  their  professions,  they  must  be  looked  down  up- 
on, and  justly  too,  as  the  lowest  in  the  scale  of  being;  as  incapable  of 
a  higli  state  of  civilization. 


MECHANICAL  ANALYSIS  OF  SOILS.  195 

to  make  examinations  which  will  indicate  the  course  of  im- 
provement. They  may  learn  all  that  is  absolutely  essential 
to  the  highest  success  in  their  profession,  and  that  which 
will  not  only  prove  the  means  of  a  competency  for  themselves 
and  families,  but  which  will  also  furnish  the  highest  means 
of  intellectual  and  moral  improvement,  and  the  sources  of 
increasing  influence  and  happiness.  This  section  will  there- 
fore be  devoted  to  the  description  of  several  modes  of  analy- 
sis, for  the  purpose  of  learning  the  composition  of  various  soils. 
It  may  serve  also  to  convince  the  farmer,  that  whether  he 
is  able  to  adopt  any  of  the  modes  himself  or  not,  the  subject 
is  one  which  appeals,  not  only  to  his  intelligence,  but  to  his 
interest,  and  to  the  dignity  of  his  profession. 

I.  Mechanical  analysis  and  tests. 

The  mechanical  analysis  of  soils  may  be  performed  by 
any  man  "  capable  of  driving  a  team  or  holding  a  plough." 

Apparatus.  The  apparatus  required  for  a  mechanical 
separation  of  the  particles  of  a  soil,  are  1st,  two  sieves,*  one  of 
copper  wire,  with  meshes  -^^  of  an  inch  square,  and  the  oth- 
er of  fine  gauze,  with  meshes  -^^^  of  an  inch  in  diameter.  2d, 
A  glass  jar,  or  common  glass  bottle.  3d,  A  balance,  capable 
of  turning  with  a  grain  weight,  and  a  set  of  weights,  from  1 
to  1000  grains.^  The  whole  need  not  cost  more  than  fifteen 
or  twenty  dollars. 

Process.  Having  selected  1000  grains  of  soil  to  be  an- 
alyzed or  tested,  heat  it,  for  twenty  minutes,  at  a  tempera- 
ture just  below  that  at  which  straw  turns  brown,  so  as  to 
evaporate  the  water.  Weigh  the  soil  again,  and  the  loss 
will  give  nearly  the  quantity  of  water  which  the  soil  is  ca- 
pable of  absorbing.  It  is  important  to  note  this,  as  some 
knowledge  may  be  obtained  from  it,  useful  to  the  farmer. 
For  example,  it  is  found  that  those  soils  which  absorb  the 


*  Sieves  brought  from  Canton,  and  sold  by   apothecaries, 
the  purpose  very  well. 


answer 


196  GEOLOGY  AND  CHEMISTRY  OF  SOILS. 

most  moisture,  are  richest  in  vegetable  mould  or  geine,  and 
by  comparing  this  power  in  different  soils,  we  may  arrive  at 
valuable  knowledge  as  to  their  comparative  fertility. 

2.  The  next  step  in  the  process  is  to  bruise  the  whole,  so 
that  no  lumps  can  be  found  in  it,  and  then  sift  it  through  the 
coarse  sieve.  What  remains  too  coarse  to  pass  through,  will 
consist  of  pebbles  and  fibres  of  wood.  This  may  now  be 
weighed  and  tested.  The  pebbles  may  be  broken  with  a 
hammer,  and  their  nature  ascertained  by  inspection,  or  they 
may  be  tested  by  acids. 

To  test  them  by  acids,  a  few  grains  may  be  bruised,  if 
need  be,  put  into  a  clean  glass,  flask  or  tumbler,  and  cover- 
ed with  water.  Half  as  much  hydrochloric  (muriatic)  acid  as 
water  may  be  added,  and  if  they  are  calcareous,  small  bub- 
bles of  gas  will  pass  up  through  the  water.  If  they  are 
wholly  carbonate  of  lime,  the  acid  will  completely  dissolve 
thefti.  But  this  is  not  to  be  expected  in  any  of  our  soils. 
It  is  very  rare,  that  the  least  trace  of  carbonate  of  lime  will 
be  found  in  this  portion.  If  the  coarse  parts  do  not  effer- 
vesce with  acids,  they  are  composed  entirely  of  silica  and 
alumina,  or  of  a  mixture  of  both,  which  is  generally  the  case. 
These  two  bodies  may  easily  be  distinguished  from  each  oth- 
er. The  silica  is  rough  like  sand,  scratches  glass,  etc.,  and 
the  alumina  is  soft  and  unctuous  to  the  touch.  If  any  ani- 
mal or  vegetable  substance  is  mixed  with  the  coarse  parti- 
cles, by  burning  a  portion  of  them,  the  odor  of  peat  or  sponge 
will  be  given  off,  then  by  carefully  weighing  a  quantity 
before  and  after  burning,  the  amount  of  organic  matter  may 
be  ascertained. 

3.  Sift  the  soil  again  through  the  fine  sieve,  and  weigh 
the  quantity  which  remains  in  the  sieve.  It  will  consist  of 
sand  and  fine  vegetable  fibres.  This  may  be  tested  in  the 
same  way  with  the  coarser  particles,  and  the  amount  ascer- 
tained. 

Take  now  the  fine  powder,  which  passes  the  gauze  sieve, 


MECHANICAL  ANALYSIS  OF  SOILS.  197 

and  agitate  it  for  a  while  in  a  given  measure  of  water,  pour 
off  the  suspended  matter  upon  a  filter.*  This  will  consist 
mostly  of  vegetable  substances,  clay  and  fine  sand.  By  ex- 
amining the  residue  in  the  glass  jar,  the  larger  particles  of 
the  mineral  ingredients  can  easily  be  detected.  Put  the  con- 
tents of  this  jar  on  the  other  filter,  and  after  the  water  has  pas- 
sed out,  the  filters  with  their  contents  may  be  weighed,  and  the 
relative  proportions  determined.  If  the  filter  contain  free  acid, 
little  lime  water  will  cause  a  white  precipitate,  which  is  either  a 
sulphuric  or  carbonic  acid ;  if  the  latter,  the  precipitate  will 
effervesce  with  sulphuric  acid,  and  will  be  converted  in- 
to gypsum,  or  sulphate  of  lime.  To  ascertain  whether  there 
is  any  sulphate  of  iron  or  copperas,  pour  into  the  liquor  a 
few  drops  of  the  infusion  of  gall-nuts,  and  it  will  give  a  dark 
or  brown  color. 

To  test  for  oxide  of  iron,  wash  the  filter,  containing  the 
clay  and  fine  particles,  with  diluted  muriatic  acid,  and  apply 
the  infusion  of  galls ;  and  if  it  becomes  black,  it  contains 
iron. 

The  above  process  can  be  easily  performed,  and  some  val- 
uable knowledge  obtained.  It  may  be  known,  for  example, 
whether  the  soil  is  mostly  silica  or  alumina,  or  whether  it 
contains  free  acid,  like  the  sulphuric,  or  whether  the  acid  is 
combined  with  oxide  of  iron,  a  substance  very  injurious  to 
vegetation ;  but  which  is,  by  the  application  of  lime  to  de- 
compose the  copperas,  easily  converted  into  gypsum  (sul- 
phate of  lime),  a  valuable  manure.  The  above  method,  how- 
ever, cannot  be  depended  upon  where  accuracy  is  required, 
and  we  will  now  proceed  to  describe  a  method  of  analysis 
which  is  very  simple,  and  which  some  farmers  may  be  able 
•to  adopt.  It  is  substantially  the  method  of  Dr.  Samuel  L. 
Dana,  of  Lowell,  Mass. 

*  The  filters  may  be  made  of  fine  linen  cloth,  of  equal  weights,. 
placed  in  a  common  glass  tunnel,  and  lined  witii  unsized  paper. 
17 


ipS  GEOLOGY  AND  CHEMISTRY  OF  SOILS. 

II.  Chemical  Analysis  of  Soils. 

Object  of  this  analysis.  The  object  of  this  analysis  is  to 
ascertain  the  water  of  absorption ;  the  quantity  of  soluble 
geine,  which  will  indicate  the  quantity  of  food  already  pre- 
pared for  vegetables  ;  the  amount  of  insoluble  geine,  which 
will  show  what  food  is  unprepared  as  yet  for  the  plant ;  salts 
of  lime  and  mineral  constituents.  The  latter  may  all  be  re- 
duced, according  to  Dr.  Dana,  to  granitic  sand;  that  is,  the 
earthy  ingredients  of  all  our  soils,  are  composed  of  the  fine 
detritus  of  granite,  gneiss,  mica  slate  and  argillite.  Now,  as 
these  earthy  ingredients  may  vary  considerably  in  their  pro- 
portions, without  affecting  the  fertility  of  the  soil,  they  are  al- 
ways prepared  for  their  office,  and  are  only  changed  for  the 
better  by  cultivation.  But  this  is  not  the  case  with  salts  and 
geine.  Any  considerable  variation  here,  will  cause  barren- 
ness. Salts  and  geine  are  the  substances  which  are  remov- 
ed by  the  plant,  and  must  therefore  be  constantly  supplied  to 
the  soil,  or  the  land  will  soon  become  exhausted.  The  great 
object  then  of  analysis,  is  to  determine  the  quantity  of  solu- 
ble and  insoluble  geine  and  salts.  This  is  all  the  farmer 
needs  to  know,  which  may  not  be  learned  by  inspection  of  the 
soil,  or  by  the  descriptions  which  have  already  been  given. 
The  relations  of  the  soil  to  heat  and  moisture,  depend  chief- 
ly upon  geine.  The  larger  the  quantity,  the  greater  the  ab- 
sorbent power  of  the  soil,  both  as  respects  water  and  ca- 
loric. 

Mode  of  Analysis.  1.  To  determine  the  absorbent  power 
of  soils,  sift  the  soil  through  a  fine  sieve,  and  take  a  quantity 
of  the  finer  portions,  and  heat  it  to  300°  F.  Then  weigh  out 
100  grains  on  a  piece  of  glazed  letter-paper,  expose  it  to  the  at- 
mosphere from  24  to  3G  hours,  weigh  again,  and  the  quan- 
tity gained  will  be  the  absorbent  power  of  the  soil.  Note 
this  in  a  Journal  kept  for  the  purpose. 

2.  To  determine  the  quantity  of  soluble  geine.     Bake  the 


CHEMICAL  ANALYSIS  OF  SOILS.  199 

soil,  which  has  passed  through  the  finer  sieve,  just  up  to  the 
point  at  which  paper  becomes  brown,  but  not  sufficiently  to 
scorch  it.  Weigh  out  100  grains  of  the  baked  soil,  as  above, 
and  boil  it  for  half  an  hour,  in  a  solution  of  .50  grains  of  sale- 
ratus,  or  carbonate  of  potassa,*  dissolved  in  4  oz.  of  water. 
When  it  has  settled,  the  clear  liquor  may  be  poured  off,  and 
the  residue  washed  in  4  oz.  of  boiling  water. 

The  whole  is  now  to  be  thrown  upon  a  filter,  which  should 
be  previously  dried  at  the  same  temperature  with  the  baked 
soil,  and  carefully  weighed.  Wash  the  soil  upon  the  filter 
until  the  water  passes  through  colorless.  If  carbonate  of  am- 
monia is  used,  instead  of  washing  the  soil,  it  should  be  di- 
gested with  the  same  quantity  of  the  solution,  at  least  twice, 
and  then  washed  until  there  is  no  alkaline  reaction  in  the 
water  as  it  passes  the  filter.  Mix  all  these  liquors  together, 
and  they  will  form  a  brown-colored  solution  containing  all  the 
soluble  geine.  The  sulphates  have  been  converted  into  car- 
bonates, which,  with  the  phosphates,  are  on  the  filter  with  the 
soil.  Dry  the  filter,  raising  the  heat  gradually  to  above  that 
of  boiling  water,  and  then  weigh  the  contents.  The  loss  is 
the  quantity  of  soluble  gcine.  Note  this  also,  and  mark  the 
filter  2. 

3.  To  test  the  accuracy  of  the  analysis  thus  far,  precipitate 
the  geine  from  the  alkaline  solution,  with  excess  of  lime-wa- 
ter. The  geine  will  combine  with  the  lime,  forming  the  ge- 
ate  of  lime,  and  when  a  sufficient  quantity  of  lime-water  has 
been  added,  the  liquor  will  be  colorless.  Throw  the  whole 
upon  a  weighed  filter,  and  wash  with  a  little  acetic,  or  very 
dilute  hydrochloric  acid,  and  this  will  combine  with  the 
lime,  and  pass  through  the  filter,  leaving  the  geine  quite  pure. 
Dry  and  weigh  as  before.     If  this  quantity  corresponds  with 

*  Dr.  C.  T.  Jackson  objects  to  carbonate  of  potassa,  because  it  is 
impoissible  to  wash  out  the  last  traces  of  it  from  the  vegetable  fibre, 
and  because  the  subcarbonate  of  potassa  takes  up  a  portion  of  the  alu- 
mina. 


209  GEOLOGY  AND  CHEMISTRY  OF  SOILS. 

that  by  the  first  process,  there  can  be  no  doubt  of  the  accu- 
racy of  the  result. 

4.  Place  the  filter  (2)  with  its  contents  upon  a  funnel,  and 
wash  with  2  drams  of  muriatic  acid,  diluted  with  3  times  its 
bulk  of  cold  water.  Wash  the  filter,  until  tasteless  water 
passes  through.  The  acid  will  dissolve  the  carbonate  and 
phosphate  of  lime;  the  iron  which  may  arise  forming  salts  of 
iron,  present  in  the  soil ;  and  the  oxide  of  iron.  The  two 
latter  exist  in  very  small  quantities  in  most  soils,  and  as  the 
sulphuret  and  sulphate  of  iron,  in  the  process  of  cultivation, 
are  converted  into  sulphate  of  lime,  the  whole  may  be  re- 
garded as  a  solution  of  the  salts  of  lime.  Evaporate  the  solu- 
tion to  dryness,  weigh  it,  and  it  will  give  the  quantity  of  these 
salts. 

5.  To  separate  these  salts,  dissolve  them  in  boiling  water. 
A  part  will  be  insoluble.  Throw  the  whole  upon  a  filter,  and 
weigh  as  above.  The  insoluble  portions  will  be  phosphate  of 
lime,  and  the  loss  will  be  the  sulphate  of  lime.  Note  the 
quantity  of  each. 

6.  To  determine  the  quantity  of  insoluble  geine.  The  re- 
sidual soil  may  now  be  burned  in  a  silver  or  platina  crucible, 
and  the  loss  of  weight  will  give  the  quantity  of  insoluble  geine 
contained  in  the  soil.  The  only  source  of  error  here,  will  be 
due  to  the  loss  of  water  in  any  hydrate  which  may  exist  in  the 
mass  burned.  But  it  is  found  by  experiment,  that  in  our 
soils  the  quantity  is  rarely  sufficient  to  affect  materially  the 
result. 

7.  The  weight  of  the  mass  after  calcination  is  *'  granitic 
sand,"  composed  mostly  of  clay,  mica  and  quartz,  all  of 
which  may  be  tested  by  methods  already  given. 

It  will  be  seen,  that  by  this  process  the  quantity  of  lime  is 
not  detected,  but  this  is  of  very  rare  occurrence  in  the  soils 
of  this  country.  From  an  analysis  of  one  hundred  and  twen- 
ty five  specimens  of  soils,  taken  from  as  many  towns  in  Mas- 
sachusetts, only  seven  contained  any  quantity  of  carbonate  of 


CHEMICAL  ANALYSIS  OF  SOILS.  201 

lime,  and  from  the  analysis  of  a  great  variety  of  soils  in  New 
England  and  the  Western  States,  only  a  few  have  any  nota- 
ble portions  of  this  substance,  although  reposing  upon  lime- 
stone rocks.  The  advantage,  therefore,  of  ascertaining  the 
quantity  of  this  substance,  may  be  derived  from  simply  test- 
ing the  soil  with  acids ;  a  method  already  described.  If 
now  the  results  of  this  analysis  are  summed  up,'  they  will  be 
arranged  in  the  following  order  : 


1.  Water  of  absorption  4.4 

2.  Soluble  geine  5.1 

3.  Phosphate  of  lime  0.6 


4.  Sulphate  of  lime  1.6 

5.  Insoluble  geine  7.5 

6.  Granitic  sand  85.2 


The  numbers  are  supplied  from  an  analysis  of  100  grains 
of  a  fertile  soil  in  Andover,  Mass. 

The  method  of  analysis  employed  by  Dr.  C.  T.  Jackson, 
differs  in  some  particulars  from  that  of  Dr.  Dana.  The 
method  employed  in  the  analysis  of  the  soils  of  Rhode  Island 
is  here  inserted. 

1.  Having  weighed  out  a  certain  quantity,  say  100  grains  of 
the  fine  soil,  that  has  passed  the  finest  sieve,  it  being  weighed 
upon  a  square  piece  of  glazed  letter-paper,  the  first  step  is  to 
dry  it  thoroughly  at  a  temperature  above  boiling  water,  but  not 
sufficient  to  scorch  the  paper.  The  soil  being  again  weighed, 
its  loss  of  weight  is  water,  and  the  amount  is  noted  in  the  la- 
boratory journal,  A. 

2.  To  ascertain  the  quantity  of  organic  matter,  whether  of 
vegetable  or  animal  origin,  we  place  the  dried  soil  in  a  platina 
crucible,  cover  it  closely,  and  heat  it  gradually  to  redness,  over 
an  alcohol  lamp.  By  the  odor  disengaged  during  the  process, 
we  know  whether  the  organic  matter  is  of  a  vegetable  or  ani- 
mal nature,  the  former  having  the  smell  of  burning  peat,  and 
the  latter  that  of  burnt  feathers.  It  is,  however,  difficult  to  dis- 
tinguish the  mixed  odors,  without  much  practice.  Having 
charred  the  organic  matter,  it  may  now  be  safely  burned  out, 
by  placing  the  open  platina  crucible  with  its  contents  in  a  clay 
muffie,  open  at  one  end,  and  exposed  to  a  full  red  heat.  The 
air  circulates  in  this  muffle,  and  soon  burns  away  all  the  or- 
ganic matter,  which  may  be  ascertained  by  repeatedly  stirring  the 
soil  with  a  platina  rod  during  its  combustion,  and  noting  wheth- 
er any  more  particles  are  burning.    After  the  operation  is  com- 

17* 


202  GEOLOGY  AND  CHEMISTRY  OF  SOILS. 

plete,  weigh  again,  and  the  loss  of  weight  is  the  amount  of  or- 
ganic matter  in  the  soil.     Note  it  in  the  laboratory  journal,  B. 

3.  To  determine  the  amount  and  nature  of  matters  soluble 
in  muriatic  acid,  which  will  take  up  all  the  mineral  substances 
that  can  be  acted  upon  by  vegetation,  such  as  all  salts  of  lime, 
iron,  alumina,  manganese,  magnesia,  potash,  etc.,  place  the 
burned  soil  B  in  a  clean  green  glass  flask,  with  a  thin  bottom, 
pour  over  it  a  small  quantity  of  distilled  water,  sufticient  to 
cover  it,  then  drop  in  some  muriatic  acid,  and  note  whether 
there  is  any  effervescence.  If  so,  there  is  a  carbonate,  proba- 
bly of  lime,  in  the  soil.  Add  more  acid,  say  about  one  ounce, 
diluted  with  an  equal  bulk  of  water.  Boil  tlie  whole,  for  half 
an  hour,  or  until  the  residuary  matter  is  nearly  white.  Every 
thing  soluble  in  the  acid  is  then  taken  up.  Dilute  with 
distilled  water  and  throw  the  whole  upon  a  double  filter.  Af- 
ter the  hquid  has  passed  through  the  paper  wash  the  insoluble 
matter  on  the  filter  by  means  of  a  stream  of  boiling  hot  water, 
and  continue  the  operation  until  the  water  comes  through  taste- 
less. Dry  the  filters  with  their  contents,  separate  them  and 
bm-n  them  separately,  weighing  one  against  the  other.  The 
difference  is  the  weight  of  the  insoluble  silicates,  and  is  gener- 
ally nearly  pure  si  lex.     Note  its  weight,  C. 

4.  In  order  to  ascertain  the  nature  and  proportions  of  the 
matters  that  have  been  dissolved  by  the  muriatic  acid,  you  may 
proceed  as  follows : 

Take  the  filtered  solution,  which  must  be  in  a  green  glass 
flask ;  add  to  it  a  few  drops  of  nitric  acid,  to  per-oxidize  the 
iron,  and  boil  it.  Then,  while  still  warm,  add  liquid  ammonia, 
until  all  the  per-oxide  of  iron  and  alumina  are  precipitated.  Sim- 
mer the  whole  a  few  minutes  so  as  to  condense  the  bulky  pre- 
cipitate. Filter  on  double  paper,  wash  the  precipitate  twelve 
hours  with  hot  water,  or  until  the  liquid  passes  tasteless  ;  then 
separate  the  })recipitate  while  moist  from  the  filter  by  means  of 
a  silver  knife,  scraping  up  every  portion  that  can  be  removed 
from  the  filter.  Place  this  in  a  large  silver  crucible  and  pour 
over  it  a  solution  of  pure  potash,  in  distilled  water.  Boil  until 
the  alumina  is  entirely  taken  up,  and  the  oxide  of  iron  left  has 
a  deep  brown  color.  You  may  know  that  a  sufticiency  of  pot- 
ash has  been  added  by  letting  fall  into  the  solution  a  drop  of 
muriatic  acid,  when  flocculi  of  alumina  will  preci[)itatp,  but  will 
immediately  redissolve  if  there  is  potash  enough.  Dilute  with 
distilled  water,  filtrate  through  double  filters,  wash  the  precipi- 
tate, dry  the  filters  and  their  contents,  sej)arate  them,  and  burn 


CHEMICAL  ANALYSIS  OF  SOILS.  203 

and  weigh  them  against  each  other.  The  difference  of  their 
weight  is  that  of  the  per-oxide  of  iron.  Mark  its  weight 
against  D. 

5.  To  separate  the  alumina,  you  must  now  take  its  alkaline 
solution  and  acidulate  it  with  muriatic  acid ;  then  add  a  solu- 
tion of  carbonate  of  ammonia  in  pure  water.  All  the  alumina 
will  be  thrown  down  in  the  state  of  a  white,  gelatinous,  and 
flocky  precipitate.  Collect  it  on  a  double  filter,  wash  it  for  24 
hours  with  boiling  distilled  water,  dry  it,  separate  and  burn  the 
filters.  Weigh  one  against  the  other,  and  the  diflference  of 
their  weight  will  be  the  weight  of  the  alumina.  Mark  this 
against  E. 

Now  you  may  go  back  to  the  ammoniacal  solution,  from  which 
the  iron  and  alumina  have  been  separated,  but  in  practice  the 
following  processes  are  carried  on  while  we  are  waiting  for  the 
filtralions  and  washings  of  the  alumina  and  oxide  of  iron. 

This  ammoniacal  solution  may  contain  the  lime,  magnesia, 
and  a  small  quantity  of  manganese.  Add  to  it  a  solution  of  ox- 
alate of  ammonia  which  will  precipitate  all  the  lime  in  the 
state  of  an  oxalate.  Let  this  precipitate  subside,  and  then  col- 
lect it  on  double  filters,  washing  it  with  warm  water.  Dry  the 
filters  with  their  contents,  separate  them  and  burn  one  against 
the  other  at  a  red  heat  in  a  platina  capsule  ;  let  fall  a  few  drops 
of  a  solution  of  carbonate  of  ammonia  upon  the  lime,  heat  it 
again  to  dull  redness.  Weigh  the  result  against  its  counter- 
poised burnt  filter,  and  you  will  have  the  quantity  of  lime  in 
the  state  of  a  carbonate,  and  may  reduce  it  by  calcidation  to 
any  other  salt  of  lime  that  you  have  found  to  exist  in  the  soih 
Mark  the  weight  of  this  against  F. 

6.  To  separate  the  magnesia,  add  to  the  solution  from  which 
the  lime  has  been  separated,  a  solution  of  phosphate  of  soda, 
(it  being  still  ammoniacal,)  when  the  magnesia  will  be  thrown 
down  in  the  state  of  an  ammoniaco-iiiagnesian  phosphate.  Col- 
lect it  on  a  filter,  wash  it  but  little,  then  dry  the  filters  and  con- 
tents, separate  them,  burn  one  against  the  other  in  a  platina 
capsule.  The  difference  of  weight  will  be  the  weight  of  the 
bi-phosphate  of  magnesia,  40  per  cent,  of  which  may  be  re- 
garded as  equivalent  to  the  magnesia  contained.     G. 

7.  You  may  now  run  a  current  of  sulphureted  hydrogen  gas 
through  the  remaining  solution,  or  add  bi-hydro  sulphate  of  am- 
monia, when  all  the  manganese  will  be  thrown  down  in  the 
state  of  a  sulphuret.     Collect  and  reduce  it  to  black  oxide.    H. 

The  analysis  is  complete  so  far  as  it  can  be  done  on  this  spe- 


204  GEOLOGY  AND  CHEMISTRY  OF  SOILS. 

cimen,  and  you  may  sum  up  your  results,  and   see  liow  nearly 
'  they  will  balance,  and  if  there  is  a  loss,  you  must  make  another 
examination  for  salts  of  potash  and  soda,  in  the  manner  I  shall 
give  presently.     Let  us  first  sum  up  the  above  operations. 

A     Water  of  absorption. 

B     Organic  matter. 

C     Insoluble  silicates. 

D     Per-oxide  of  iron. 

E     Alumina. 

F     Lime. 

G     Magnesia. 

H  Manganese. 
In  order  to  ascertain  the  existence  of  alkaline  salts,  burn  off 
the  vegetable  matter  from  another  100  grains  of  the  dry  soil. 
Then  pour  over  it  a  little  nitric  acid,  and  digest  it  at  a  boiling 
heat.  Dilute  and  filter  the  solution,  evaporate  it  to  entire  dry- 
ness, fiise  the  saline  matter  obtained,  and  drop  into  it  a  few 
fragments  of  prepared  pure  charcoal.  If  nitrates  are  present, 
deflagration  will  take  place,  and  the  alkaline  bases  will  be  con- 
verted into  carbonates.  Dissolve  the  residue  and  test  a  drop 
of  the  solution  by  means  of  a  solution  of  chloride  of  platina  and 
soda.  If  potash  is  present,  a  yellow  powder  will  precipitate, 
but  none  will  fall  if  soda  alone  is  present. 

Sect.  2.  Composition  of  Soils  as  cUter mined  hy  Analysis. 
The  composition  of  soils  might  generally  be  deduced  from 
the  composition  of  the  rocks  out  of  which  they  are  formed, 
provided  no  chemical  nor  mechanical  changes  were  wrought 
upon  them  in  the  process  of  disintegration.  But  as  the 
proportion  of  the  ingredients  are  changed  in  this  process, 
as  some  of  the  alkalies  are  abstracted  by  growing  plants,  or 
removed  by  successive  crops,  and  as  organic  matters  are 
added,  we  must  resort  to  an  examination  by  analysis,  in  or- 
der to  ascertain  the  exact  composition  of  any  soil  which  is 
presented  for  our  inspection.  By  this  examination,  soils  are 
found  to  be  composed  of  two  parts:  1.  the  mineral  ingredi- 
ents, or  inorganic  portions,  which  include  the  alkalies,  metal- 
lic oxides,  salts  and  earths  ;     2.  the  vegetable  and  animal 


MINERAL  CONSTITUENTS  OF  SOIL.  205 

I.  Mineral  constituents  of  soils.  The  mineral  substances 
which  enter  into  the  composition  of  all  soils,  are  few  in  num- 
ber, and  most  of  them  easily  detected.  They  may  be  divided 
into  3  classes :  1.  earths ;  2.  alkalies  and  metallic  oxides  ; 
3.  salts  and  urets. 

As  the  rocks  are  mostly  made  up  of  silica,  alumina,  lime 
and  magnesia,  the  great  mass  of  the  soil  is  composed  of  these 
substances,  which  are  commonly  called  earths.  The  alkalies, 
potassa,  soda  and  ammonia,  the  metallic  oxides  of  iron  and 
manganese,  exist  in  all  fertile  soils  in  small  quantities.  The 
phosphates  of  lime  and  magnesia,  nitrate  of  potash,  sulphates 
of  lime  and  ammonia,  chloride  of  sodium,  carbonates  and 
other  salts,  are  almost  always  present  in  soils  ;  and,  in  some 
cases,  sulphurets,  phosphurets  and  carburets  of  iron  exist  in 
very  small  quantities. 

In  one  view  of  the  subject,  the  soils  are  a  mass  •  of 
salts,  mostly  silicates,  silicic  being  the  most  abundant  and 
most  powerful  acid  in  nature.  We  should  expect,  from  the 
composition  of  the  simple  minerals  which  form  the  rocks,  that 
the  soils,  considered  chemically,  would  be  a  mass  of  silicates. 
But  it  will  be  a  more  practical  view,  and  better  accord  with 
the  general  representation  of  agricultural  writers,  to  describe 
silicic  acid  among  the  earths,  alumina,  lime  and  magnesia. 
We  have  already  described  these  earths,  in  their  principal 
chemical  characters  and  in  their  relations  to  the  rocks.  We 
come  now  to  consider  them  agriculturally,  and  shall  notice 
their  amount  in  soils,  their  relations  to  the  vegetable  king- 
dom, and  their  fitness  to  perform  the  duties  assigned  them  in 
the  vegetable  economy. 

When  soils  are  examined  by  chemical  analysis,  they  are 
found  to  be  composed  of  the  following  mineral  substances. 

1.  Silica  or  silicic  acid,  also  called  silex  and  siliceous  earth, 
constitutes  about  40  or  45  per  cent,  of  the  crust  of  the  globe, 
and  66  per  cent,  of  all  the  rocks  and  soils  of  New  England. 
This  proportion  varies  but  slightly,  with  regard  to  all  soils, 


206  GEOLOGY  AND  CHEMISTRY  OF  SOILS. 

capable  of  sustaining  a  healthy  vegetation,  with  the  exception, 
perhaps,  of  limited  portions  of  calcareous  and  peaty  soils,  in 
which  the  proportion  is  much  less,  but  generally  greater  than 
66  parts  in  100. 

The  properties  of  silica  render  it  well  fitted  to  form  so  large 
a  portion  of  the  soil.  It  is  nearly  insoluble  in  water,  and 
hence  is  not  liable  to  be  washed  away  by  rains.  In  fact  it  is 
not  dissolved  by  any  acid  found  in  the  soil,  unless  it  be  the 
crenic  and  hydrofluoric,  in  which  state  it  may  be  introduced 
into  the  organs  of  plants.  Silica  is  not  an  acid,  by  the  chemi- 
cal tests,  because  of  its  insolubility.  It  however  combines 
with  the  alkaline  bases,  with  the  earths  and  metallic  oxides, 
and  is  the  most  powerful  electro-negative  element  in  the  com- 
position of  the  soil.  It  acts  in  the  soil  as  an  acid,  and  bal- 
ances, by  its  negative  character,  almost  the  entire  mass  of  the 
electro-positive  earths,  alkalies  and  metallic  oxides.  Its  power 
of  absorbing  and  retaining  water,  is  very  slight,  and  hence 
when  it  is  the  principal  ingredient  of  a  soil,  it  imparts  to  it  a 
porous,  dry  and  light  character.  The  relations  of  silica 
to  vegetation  are  highly  interesting.  It  is  almost  the  only 
ingredient  of  soils  which  gives  to  them  the  property  of  per- 
mitting the  roots  of  plants  to  extend  themselves  in  all  direc- 
tions, and  forms  as  we  have  seen,  p.  175,  a  part  of  the  vege- 
table structure.  Silica  thus  furnishes  the  principal  support 
to  the  cultivated  grains  and  grasses,  and  defends  them  from 
the  action  of  atmospherical  and  other  agents. 

2.  Aluminous  earths.  Alumina,  a  sesquioxide  of  alumina, 
is  composed,  as  we  have  seen  p.  175,  of  27.4  parts  by  weight 
of  the  metal  aluminium,  and  24  parts  of  oxygen.  It  is  found 
in  every  region  of  the  globe,  and  in  the  rocks  of  all  ages.  It 
results  from  the  decomposition  of  the  feldspathic  minerals  or 
argillaceous  rocks.  The  different  kinds  of  clay  of  which 
bricks,  pipes  and  earthen  ware  are  made,  consist  of  hiclratc 
of  alumina,  that  is,  of  alumina  combined  with  water,  and  of 
a  small  portion  of  silica.     Aluminous  earth  is  next  to  silica 


MINERAL  CONSTITUENTS  OF  SOIL.  207 

in  quantity,  and  constitutes  but  about  16  per  cent,  of  all  the 
soils  in  New  England.  It  varies  greatly  in  different  varieties 
of  soil,  though  it  is  never  absent  from  any.  Pure  alumina, 
however,  does  not  exist  in  the  soil.  It  is  generally  combined 
with  silica,  and  with  organic  acids,  such  as  crenic  and  apo- 
crenic  acids,  and  geic  or  humic  acid. 

The  properties  of  aluminous  earth  make  it  a  fit  associate 
for  silica,  in  order  to  give  the  proper  texture  and  adhesive- 
ness to  the  soil.  Like  silica,  it  is  insoluble  in  water.  But 
its  action  upon  the  roots  of  vegetables,  is  just  the  opposite  of 
silica,  giving  the  roots  their  basis  of  action  and  support, 
and  preventing  them  from  penetrating  too  far.  It  retains  the 
water  with  great  force,  but  yields  it  to  the  plant  as  its  wants 
may  require.  In  consequence  of  its  pow  er  of  absorbing  and 
retaining  water,  when  it  constitutes  a  large  proportion  of  the 
soil,  it  is  unfriendly  to  vegetation,  forming  a  soft,  ductile  paste, 
which  excludes  the  air  in  wet  weather,  and  contracts  and 
bakes  in  seasons  of  drought.  As  it  contracts  by  heat,  the 
delicate  fibres  of  the  roots  are  injured  in  the  fissures  thus 
formed,  by  exposure  to  the  cold,  heat  and  water. 

Aluminous  earth  is  still  more  nearly  allied  to  vegetables 
by  forming  a  part  of  their  structure.  The  ashes  of  some 
plants  contain  very  small  portions  of  it.  It  is  also  found  in  the 
seeds  of  some  grains.  It  is  capable  of  acting  the  part,  both 
of  an  acid  and  of  an  alkali,  a  circumstance  which  renders  it 
probable,  that  its  chief  agency  in  the  soil,  is  to  act  upon  the 
vegetable  matter,  and  convert  it  into  veoetable  food.  Alu- 
mina  is  farther  serviceable,  from  its  possessing  the  property 
of  absorbing  gaseous  bodies,  such  as  ammonia,  and  of  retain- 
ing in  the  soil  for  the  use  of  the  plant,  what  would  otherwise 
escape  into  the  air.  The  fermentation  of  manures  in  the 
soil,  yield  several  gases,  which  are  retained  in  this  way. 

3.  Lime.  Lime  is  also  widely  disseminated  in  nature.  It 
forms  the  basis  of  extensive  mountain  ranges,  and  of  a  large 
portion  of  the  cultivated  surface  of  the  earth.     It  exists,  how- 


208  GEOLOGY  AND  CHEMISTRY    OF  SOILS. 

ever,  not  in  its  pure  or  caustic  state,  but  combined  with  acids, 
forming  with  carbonic  acid  the  carbonate  of  lime  (marble), 
which  is  the  most  abundant.  In  this  form,  it  constitutes  about 
^  part  of  the  crust  of  the  globe.  The  sulphate  (common  plaster) 
is  next  in  abundance,  and  the  phosphate  is  diffused  through  all 
soils,  and  is  the  source  from  which  animafls  obtain  their  bones. 
The  pure  or  quick  lime  is  generally  obtained  by  heating  the 
carbonate  in  kilns,  until  all  the  carbonic  acid  is  driven  off.  It 
will  then  unite  with  water,  and  form  a  white  bulky  hydrate, 
called  slacked  lime,  used  for  mortar. 

The  quantity  of  lime,  found  in  the  soils  of  this  country,  is 
generally  very  small.  From  an  analysis  of  the  soils  of  Mas- 
sachusetts, as  contained  in  the  report  of  Prof  Hitchcock, 
lime,  in  the  form  of  carbonate,  sulphate  and  phosphate,  does 
not  upon  an  average  exceed  3  per  cent.  The  sulphate  is 
the  most  abundant,  varying  from  0.1  to  3.9  per  cent. 

The  carbonate  of  lime,  with  the  exception  of  one  soil,  in 
Truro,  which  contains  21.3  per  cent,  varies  from  mere  traces 
of  it,  to  6  per  cent, ;  but  generally  there  is  much  less  than 
2  per  cent.,  and  not  one  soil  in  twenty,  contains  a  single  par- 
ticle of  lime  in  the  state  of  carbonate.  The  amount  of  phos- 
phate is  not  accurately  determined,  but  the  proportion  in 
most  soils  is  less  than  1  per  cent.  The  soils  of  Rhode  Isl- 
and, according  to  the  analysis  of  Dr.  C.  T.  Jackson,  do 
not,  upon  an  average,  contain  1  per  cent,  of  all  the  salts  of 
lime,  and  scarcely  1  per  cent,  is  found  in  the  soils  of  New 
Hampshire. 

Soils  from  the  Western,  Middle,  and  Southern  States,  al- 
though from  lime-stone  regions,  rarely  contain  a  larger  pro- 
portion of  lime,  in  any  form  than  is  found  in  New  England. 
It  appears  from  an  analysis  of  five  specimens  of  soil  from  Il- 
linois and  Ohio,  that  all  the  salts  of  lime  amounted,  upon  an 
average,  only  to  4.9  per  cent. 

In  other  countries,  soils  are  frequently  described,  contain- 
ing from  6  to  30  per  cent,  of  the  carbonate  alone.     In  this 


MINERAL  CONSTITUENTS  OF  SOIL.  209 

respect,  then,  our  soils  are  peculiar,  and  hence  the  great  im- 
portance attached  to  this  substance  as  a  manure.  (See  im- 
provement of  the  soil.)  The  reason  why  so  small  a  quantity 
of  carbonate  of  lime  is  found  in  our  soils,  compared  with  those 
in  other  countries,  is  ascribed  by  Prof.  Hitchcock  to  the  fact 
that  growing  plants  abstract  it,  and  that  our  lime  rocks  are 
not  so  easily  reduced  to  the  state  of  soil  by  the  ordinary 
agents  of  disintegration. 

The  influence  of  lime  upon  growing  vegetables  is  not,  in 
this  country,  due  to  the  texture  which  it  gives  to  the  soil,  for 
in  most  cases,  the  quantity  is  not  sufl[icient  to  render  a  heavy 
soil  light,  or  modify  the  influence  of  too  great  a  quantity  of 
siliceous  sand.  Its  influence  is  probably  threefold.  1.  It 
tends  to  convert  the  vegetable  matter  into  vegetable  food, 
thus  performing  the  office  of  a  solvent,  or  converter  of  innu- 
tritious  matter  into  nutriment.  2.  It  corrects  the  acidity  of 
soils,  by  uniting  with  free  acids,  or  decomposing  poisonous, 
metallic  salts.  3.  It  forms  a  part  of  the  vegetable  struc- 
ture, and  is  properly  inorganic  food.  Like  all  other  alkalies 
it  also  contributes  to  electrical  effects,  which  may  be  regarded 
as  a  kind  of  stimulus  to  the  vital  functions.  It  is  found,  as 
we  have  seen,  in  the  vegetable  productions,  sometimes  uni- 
ted with  organic,  and  at  others,  with  inorganic  acids. 

4.  Magnesia.  Magnesia  is  found  in  serpentine  in  the 
form  of  a  silicate,  in  steatite  or  soap-stone,  talcose  slate,  in 
magnesite,  sea  water,  certain  limestones,  called  magnesian 
limestone  or  dolomite.  Although  generally  found  in  soils,  it 
never  constitutes  but  a  small  portion  of  them.  The  quan- 
tity is  given  in  but  a  hw  of  the  soils  of  Massachusetts,  and 
varies  from  .25  to  2J  per  cent,  from  which  it  is  inferred,  that 
only  traces  of  it  exist.  In  the  soils  of  Rhode  Island,  the 
amount  of  magnesia  is  rarely  1  per  cent. ;  often  none  at  all, 
or  only  traces  are  found.  A  few  soils  contain  4  per  cent. 
In  New  Hampshire  less  than  1  per  cent,  is  found,  and  in 
Maine,  out  of  thirty-five  soils  analyzed,  only  one  contained 
18 


210  GEOLOGY  AND  CHEMISTRY  OF  SOILS. 

any  magnesia,  and  that  contained  3  per  cent.  It  must,  how- 
ever, exist  in  all  fertile  soils,  as  it  enters  into  the  composition 
of  many  varieties  of  grain.  The  kernel  of  corn  could  not 
be  formed  without  the  presence  of  the  phosphate  of  magnesia. 
Magnesia,  like  lime,  does  not  generally  constitute  a  suffi- 
ciently large  portion  of  the  soil  to  affect  its  texture.  "When 
it  does  it  has  the  properties  of  clay,  absorbing  moisture  and 
imparting  its  adhesive  properties.  It  acts  as  an  alkali,  to 
convert  vegetable  matter  into  food,  and  constitutes  a  part  of 
the  vegetable  structure.  When  applied  in  its  caustic  state, 
it  has  been  found  injurious  to  vegetation  ;  but  as  a  carbonate, 
it  is  highly  useful.  Like  lime,  it  must  be  regarded  as  an  im- 
prover of  the  soil,  as  a  manure,  rather  than  an  earth. 

The  union  of  these  four  earths  in  a  soil,  give  to  it  gener- 
ally the  properties  of  each.  But  as  they  are  combined  in 
the  soil  with  each  other,  and  with  other  substances,  in  the 
form  of  salts,  we  cannot  infer  with  certainty  the  exact  char- 
acter of  the  soil,  by  knowing  in  what  proportions  they  ex- 
ist ;  but  we  must  know  in  what  state  of  combination  they 
are  found.  It  will  be  seen  that  silica  and  alumina  constitute 
almost  the  entire  mass  of  the  earthy  ingredients  of  all  our  soils, 
and  the  qualities  of  a  good  soil  will  depend  upon  the  right 
proportion  of  these  substances.  But  there  are  other  inorganic 
bodies  found  in  soils,  as  essential  to  fertility  as  any  that  have 
been  described. 

2.  Alkalies  and  metallic  oxides,  contained  in  the  soil.  The 
most  important,  and  almost  the  only  substances  under  this 
head,  are  ammonia,  potash,  soda,  oxide  of  iron  and  manga- 
nese. 

Ammonia  has  been  shown  by  Liebig  to  exist  in  the  atmos- 
phere, in  very  small  quantities;  of  course,  inconsequence  of 
its  solubility  in  water,  it  is  found  in  all  soils.  It  has  been 
supposed,  that  ammonia  was  a  product  of  the  putrefaction  of 
animal  and  vegetable  substances,  containing  nitrogen.  But 
Liebig  believes,  that  it  belongs  to  the  original   formation  of 


MINERAL  CONSTITUENTS  OF  SOIL.  211 

the  matter  of  the  earth,  and  Daubeny  points  out  its  source  as 
proceeding  from  volcanic  action.  The  exact  amount  in  the 
atmosphere  or  the  soil  has  not  been  accurately  determined. 
It  is  found  in  iron-rust,  clay,  etc.,  and  is  retained  in  the  soil 
in  the  form  of  sulphate,  carbonate,  humate,  etc. 

Its  relations  to  vegetation  are  of  the  highest  importance. 
According  to  Liebig,  it  is  the  only  source  of  the  nitrogen  of 
plants.  Others  regard  it  as  the  solvent  of  geine,  and  the  con- 
verter of  the  vegetable  matter  into  food  ;  and  some  add,  that 
it  stimulates  the  functions  of  plants.  Its  action  has  already 
been  considered  in  the  third  chapter. 

Potassa  or  potash.  Pure  potassa  is  not  found  in  soils.  It 
is  a  well  known  alkali  originating  from  several  rocks,  in 
which  it  exists  mostly  in  combination  with  silicic  acid  {sili- 
cate of  potash),  but  it  is  also  found  combined  with  several 
other  acids. 

The  minerals  which  supply  potash  to  plants  are  numerous 
and  widely  diffused.  All  the  aluminous  minerals  contain  it. 
Feldspar,  a  constituent  of  granite,  contains  I7:|  per  cent. 
Basalt  contains  from  |^  to  3  per  cent.,  clay-slate  from  2.75  to 
3.36,  and  loam  from  IJ  to  4  per  cent.  Hence  we  should 
expect  to  find  potash  in  large  quantities  in  the  soil ;  but  owing 
to  the  action  of  growing  plants  which  eliminate  the  potash,  soils 
which  have  been  cultivated  for  some  time,  contain  much  less 
than  might  appear  from  its  abundance  in  the  rocks.  This  is 
a  case,  in  which  analysis  must  be  resorted  to,  in  order  to  de- 
termine the  exact  amount  of  an  ingredient.  In  the  recent 
analysis  of  the  soils  of  New  England,  we  have  been  unable  to 
find  potash  as  an  ingredient,  although  it  must  exist  in  all  our 
soils  in  a  greater  or  less  quantity,  locked  up  in  the  minerals. 
Dana  estimates  its  amount  in  the  soil,  composed  of  granitic 
sand,  to  be  36  tons  per  acre,  6  inches  in  depth.  In  some 
soils,  it  is  found  to  constitute  from  5  to  10  per  cent. 

The  relation  of  potash  to  vegetation  is  similar  to  all  alkaline 
substances.     It  is  a  powerful  converter  of  vegetable  matter 


212  GEOLOGY  AND  CHEMISTRY  OF  SOILS. 

into  the  food  of  plants.  It  neutralizes  acids,  and,  by  uniting 
with  silicic  acid,  forms  the  outer  covering  or  epidermis  of 
the  grains  and  grasses.  It  is  found  in  all  plants  in  considera- 
ble abundance,  and  is  one  of  the  greatest  fertilizers  of  the 
soil.  Plants,  as  we  have  frequently  remarked,  eliminate  it 
from  the  rocks  by  galvanic  action  ;  decomposing  vegetable 
matter  also  abstracts  it  ;  the  ordinary  action  of  the  air,  wa- 
ter, and  many  other  agents:  hence  the  use  of  clay,  ashes, 
of  fallow  crops,  and  ploughing  in  green  crops,  to  induce  the 
soil  to  yield  its  potash. 

tSoda,  as  we  have  seen,  is  a  constituent  of  many  minerals, 
such  as  albite  containing  11.43  per  cent.,  mica  contain- 
ing from  3  to  5  per  cent.,  and  basalt  from  5  to  7  per  cent,  of 
this  alkali.  But  the  proportion  in  the  soil  is  much  less,  in 
consequence  of  the  action  of  growing  plants, — many  of  which 
take  up  and  appropriate  it  as  food.  Common  salt  is  a  chloride 
of  sodium,  and  is  found  very  widely  diffused,  so  that  this  al- 
kali exists  probably  in  sufficient  quantities  in  the  soil  to  sup- 
ply all  the  wants  of  plants.  Its  action  is  similar  to  potassa, 
but  it  is  not  so  essential  to  vegetation.  Porphyritic  soils  con- 
tain it  in  the  greatest  abundance. 

Oxide  of  iron  exists  in  the  soil  as  a  protoxide,  peroxide 
and  in  combination  with  acids.  It  is  found  in  all  soils,  in 
one  or  all  of  these  forms.  The  use  of  clay  has  been  supposed 
to  result  from  its  containing  from  9  to  13  per  cent,  of  this 
substance.  It  is  also  found  in  green  sand  in  great  abundance, 
constituting  about  |-  part  of  the  whole  mass.  In  fact,  it  is 
widely  diffused  through  all  the  primitive  and  most  of  the 
secondary  rocks. 

The  quantity  of  oxide  of  iron  as  determined  by  analysis, 
varies  considerably  in  different  soils,  from  1  to  5  per  cent,  in 
the  soils  of  Massachusetts.  The  soils  of  Maine  contain  from 
2  to  12  per  cent.,  those  of  Rhode  Island  from  2  to  8  per 
cent.,  and  generally  soils  contain  at  least  5  per  cent,  of  this 
oxide. 


MINERAL  CONSTITUENTS  OF  SOIL.  213 

The  protoxide  of  iron  is  generally  unfavorable  to  vegeta- 
tion, but  the  peroxide  seems  to  act  the  part  of  an  alkali,  con- 
verting the  vegetable  substances  into  the  proper  state  to  be 
absorbed  by  the  roots  of  plants,  while  the  protoxide  does  not. 
Dr.  Dana  says,  that  if"  iron  peroxidates  itself  in  contact  with 
vegetable  fhre,  the  texture  of  the  vegetable  fibre  is  weakened, 
and  geine  is  produced,  and  that  in  a  few  hours.  It  is  during 
the  passage  from  protoxide  to  peroxide,  that  the  'saponifying^ 
action  takes  place,  geine  is  produced,  and  then  combines  with 
the  peroxide.''^ 

Oxide  of  iron  is  also  found  in  the  vegetable  substance,  and 
must  be  carried  there  in  some  of  its  combinations  with  acids, 
as  the  oxide  is  insoluble.  It  probably  combines  for  this  pur- 
pose, with  some  of  the  organic  acids  in  vegetable  mould, 
such  as  crenic  or  humic  acids,  or  both,  and  thus  acts  the  part 
of  a  base  to  those  acids,  which  are  the  products  of  the  living 
principle. 

Crenate  of  iron  and  of  alumina  are  deposited  in  iron  tanks 
where  river  water  runs.  Liebig  regards  the  oxide  as  perform- 
ing the  office  of  absorbing  and  retaining  ammonia. 

Oxide  of  manganese.  But  very  small  quantities  of  this  ox- 
ide are  found  in  soils,  and  still  smaller  quantities  in  plants. 
It  probably  acts  in  a  manner  similar  to  oxide  of  iron,  forming 
a  base  for  the  combination  of  the  humic  or  crenic  acids. 

3.  Salts  and  Urets.  Under  this  head,  are  included  sev- 
eral compounds  which  analysis  has  detected  in  soils.  Such 
as  common  salt,  sub-phosphate  of  alumina,  phosphate  of  lime, 
nitrate  of  potash  and  of  soda,  sulphate  of  lime,  sulphate  of 
iron  (copperas),  sulphuret  of  iron,  etc.  Some  of  these  sub- 
stances have  received  attention  in  other  places,  and  but  a 
few  remarks  are  required  to  show  what  is  most  important  to 
be  noticed  respecting  them. 

Common  salt,  or  chloride  of  sodium,  constitutes  about  2 J 
per  cent,  of  sea-water.     It  also  exists  in  the  rocks,  especially 
in  the  new  red  sand-stone.     It  seems  to  act  as  an  alkali,  by 
,  18* 


214  GEOLOGY  AND  CHEMISTRY  OF  SOILS. 

furnishing  soda  to  plants.  The  quantity  in  the  soil  is  ex- 
ceedingly small,  but  only  small  quantities  are  wanted.  The 
chlorine,  which  plants  sometimes  exhale,  must  come  from  this 
substance.     It  is  highly  useful  on  some  soils. 

Sub-phosphate  of  alumina  and  phosphate  of  lime  may  be 
noticed  here  in  connection,  because  they  have  lately  been 
shown  to  be  present  in  all  fertile  soils.  Phosphate  of  lime  is 
the  most  common  form  in  which  both  the  lime  and  the  phos- 
phoric acid  exist. 

It  is  from  these  substances,  that  animals  obtain  their  phos- 
phorus. About  50  per  cent,  of  bones  is  phosphate  of  lime. 
Almost  all  the  vegetable  products  contain  it,  whether  the 
land  has  been  cultivated  or  not.  It  even  exists  in  the  pollen 
of  the  pine  in  forests. 

Nitrate  of  potash  and  nitrate  of  soda  are  sometimes  de- 
tected in  soils. 

Sulphate  of  iron  is  also  detected  in  a  few  soils,  and  is 
highly  poisonous  in  its  effects.  Lime  converts  it  into  gyp- 
sum and  oxide  of  iron,  thus  rendering  it  a  valuable  saline 
manure. 

Sulphuret  of  iron  is  found  in  considerable  quantities,  but 
by  exposure  to  air  and  water,  it  changes,  first  to  the  sulphate 
of  iron,  and  then,  by  the  action  of  lime,  to  the  sulphate  of 
lime,  as  above. 

Carbonic  acid  in  a  free  state  is  also  found  in  soils,  the 
quantity  varying  with  circumstances.  The  action  of  this  acid 
has  been  fully  discussed.  One  fact  of  a  highly  practical  value 
is,  that  the  urcts  are  constantly  becoming  salts,  so  that  the 
soil  is  often  found  to  contain  a  larger  quantity  of  salts  than  the 
rocks.  The  process  of  disintegration  produces  changes  in 
the  arrangement  of  the  simple  elements. 

Thus  we  have  enumerated  all  the  inorganic  bodies,  which 
are  found  in  the  soil,  as  ascertained  by  analysis,  and  their 
general  relations  to  growing  plants.  From  this  examination 
soils  are  composed,  generally,  of  the 


ORGANIC  PORTIONS  OF  THE  SOIL.  215 


Earths,  Mkalies, 


Silica  66.  per  cent. 

Alumina  16.        " 

Magnesia  1.        " 

Lime  2.        " 

Oxides, 
Of  Iron 
Of  Manganese 


per  cent. 


Potash  2.  per  cent. 

Soda  .5      " 

Ammonia  .5      " 


Salts  and  Urets,     1.5  per  cent 
Organic  matter,     6.5        " 


II.  Organic  constituents  of  the  soil.  A  proper  mixture  of 
organic  matters  with  the  mineral  ingredients,  is  essential  to 
the  fertility  of  the  soil,  and  hence  vegetable  or  animal  sub- 
stances are  always  found  in  soils  capable  of  cultivation.  These 
organic  matters  are  derived  from  the  roots  and  other  parts  of 
plants,  or  from  the  application  of  manures.  The  substance 
which  is  formed  by  the  decay  of  these  organic  products,  and 
which  has  been  supposed  to  give  fertility  to  the  soil,  is  called 
by  several  names,  as  humus,  geine,  vegetable  mould,  etc.  and 
is  intended  to  include  all  the  decaying  organic  matter  of  the 
soil.  It  is  a  brownish  or  black  substance,  and  when  it  be- 
comes intimately  mixed  with  the  mineral  ingredients,  it  im- 
parts a  black  color  to  the  soil,  a  greater  power  of  absorbing 
water  and  gaseous  substances,  renders  it  more  permeable  to 
air  and  to  the  roots  of  plants,  improves  its  texture,  and  in- 
creases its  power  of  absorbing  and  retaining  heat. 

This  remarkable  substance,  a  history*  of  which  has  al- 
ready been  given,  p.  138,  is  composed,  as  we  have  seen, 
of  the  following  substances :  Jiumin,  extract  of  humus, 
humic  acid,  crenic  and  apocrenic  acids,  which  are  generally 
combined  with  the  bases,  lime,  magnesia,  soda  or  potash, 
ammonia,  alumina,  oxide  of  manganese,  and  per-oxide  of  iron. 
When  therefore  we  examine  the  organic  constituents,  by  anal- 
ysis, we  find  the  following  substances. 

1.  Humic  acid,  which  is  identical  in  composition  with  hu- 

*  Dr.  Dana,  in  his  Muck  Manual,  has  given  a  history  of  this  sub- 
stance, and  advocates  the  use  of  the  terra  geine. 


216 


GEOLOGY  AND  CHEMISTRY  OF  SOILS. 


min.  The  quantity  of  this  acid,  contained  in  any  given  por- 
tion of  soil,  may  be  determined,  very  nearly,  by  the  proportion 
of  vegetable  matter,  dissolved  by  the  application  of  alkalies. 

The  following  is  the  proportion  of  the  soluble  matter, 
called  soluble  geine,  nearly  identical  with  humic  acid,  and  of 
insoluble  geine  (humin),  contained  in  the  soils  of  Massachu- 
setts, from  the  different  geological  formations. 


Soluble  Geine.                     Insoluble  Geine 

Alluvium 

2.25 

.    2.15 

Tertiary  argillaceous 

soils 

3.94 

5.22 

Sandstone 

(( 

3.28 

.    2.14 

Graywacke 

(( 

3.60 

.        .        .        .        4.00 

Argillaceous  slate 

(( 

5.77 

.    4.53 

Limestone 

" 

3.40 

4.04 

Mica  slate 

(( 

4.34 

.    4.60 

Talcose  slate 

C( 

3.67 

.        .        .        .        4.60 

Gneiss 

(( 

4.30 

.    3.40 

Granite 

(( 

4.05 

.        .        .        3.87 

Sienite 

(( 

4.40 

.    4.50 

Porphyry 

(( 

5.97 

4.10 

Greenstone 

(( 

4.56 

.    6.10 

The  soluble  geine,  of  course,  is  not  all  humic  acid,  as  other 
acids  and  salts  are  dissolved  by  the  alkalies ;  still,  there  is  not 
much  reason  to  doubt,  but  that  there  is  from  1  to  3  per  cent, 
of  this  acid  in  all  fertile  soils. 

2.  Crenic  acid  was  first  discovered  by  Berzelius,  in  1832, 
in  the  water  of  Porla  well,  near  Orebro,  in  Sweden.  It  exists 
in  all  our  soils,  and  in  the  waters  of  rivers  and  ponds,  and  is 
generally  associated  with  apocrenic  acid,  and  combined  with 
bases. 

Both  of  these  acids  may  be  precipitated  from  their  neu- 
tral solutions  by  means  of  subacetate  of  lead,  and  may  be 
separated  from  each  other  by  the  salts  of  copper. 

It  is  difficult  to  determine  the  quantity  of  this  acid.  Soils, 
analyzed  by  Berzelius,  contained  two  per  cent. 


ORGANIC  PORTIONS  OF  SOIL.  217 

The  crenic  acid  has  been  detected  in  the  sub-soil,  and  this 
may  account  for  the  utility  of  sub-soil  ploughing.  It  is  also 
found  in  river  water,  and  may  account  for  the  effects  of  irri- 
gation. The  compounds  of  crenic  acid,  described  p.  136, 
are  also  found  in  small  quantities  in  the  soil. 

Apocrcnic  acid  is  formed,  as  its  name  imports,  from  the 
crenic,  by  simply  exposing  the  latter  to  the  air.  It  was  found 
in  the  water  of  Porla  well,  in  connection  with  the  crenic  acid. 
This  acid  is  found  in  very  small  quantities ;  in  some  soils,  ac- 
cording to  Berzelius,  about  two  per  cent. 

As  all  the  alkalies  dissolve  these  two  acids,  and  as  the  al- 
kaline earths  render  the  inert  crenates  active,  we  can  seethe 
utility  of  adding  alkaline  substances  to  the  soil  to  act  upon 
these  acids,  and  to  bring  them  into  a  fit  state  to  enter  the  vege- 
table organs. 

"  The  remarks  of  De  Saussure  on  soils,"  says  Berzelius, 
"  seem  to  show,  that  the  three  constituents  above  described, 
crenic,  apocrenic  and  humic  acids,  by  means  of  the  recipro- 
cal influence  of  water  and  air,  become  mutually  changed. 
Water  in  moist  soil,  changes  a  part  of  the  insoluble  humin 
into  humic  acid  ;  so  that,  after  a  sufficient  length  of  time,  the 
greater  part  of  the  humin  becomes  soluble.  The  atmosphere, 
on  the  other  hand,  re-forms,  from  the  soluble  matter,  humin. 
Coal  of  humus,  which  in  contact  with  the  air  changes  a  por- 
tion of  it  into  carbonic  acid,  is  itself  converted  into  humin 
and  humic  acid,  and  this  appears  in  fact  to  be  the  useful  ef- 
fect of  loosening  the  soil  by  tillage  which  exposes  it  to  the 
influence  of  the  air." 

The  extract  of  humus  and  glarin  are  brown  matters,  mostly 
composed  of  carbon,  hydrogen,  and  oxygen ;  and,  so  far  as 
we  know,  are  of  little  use  to  vegetation,  in  their  pure  state. 
They  may  furnish  matter  for  nutriment,  after  being  acted  up- 
on by  the  air  or  alkalies. 

Dr.  C.  T.  Jackson  states,  that  the  substances  which  are 
confounded  under  the  name  of  soluble  humus,  soluble  geine. 


218  GEOLOGY  AND  CHEMISTRY  OF  SOILS. 

etc.  consist  of  several  substances  aJready  referred  to.  Dr. 
Dana  calls  the  whole  geine,  and  as  the  fertility  of  a  soil  de- 
pends upon  the  soluble  geine  and  salts,  his  method  of  analysis 
is  well  adapted  to  determine  their  amount,  and  the  conse- 
quent fertility  of  the  soil. 

But  whatever  views  are  adopted,  relative  to  the  nature  of 
the  organic  constituents  of  soils,  the  fact  is  fully  established 
by  experience,  that  a  due  mixture  of  organic,  with  the  mine- 
ral ingredients,  is  essential  to  fertility,  and  that  the  power  of 
the  soil  to  bear  successive  crops  for  a  series  of  years,  depends 
upon  keeping  up  the  supply  of  humus  and  salts,  which  a  con- 
tinued course  of  cropping  takes  away.  Other  substances 
must  exist  also  in  the  soil,  in  a  state  of  partial  decomposition, 
such  as  the  various  vegetable  products,  but  they  all  finally 
pass  into  those  above  described,  or  pass  off  in  gases,  such  as 
ammonia,  sulphureted  hydrogen,  and  carbonic  acid. 

Sect.  3.    Theory  of  the  mutual  action  of  the  inorganic  and 
organic  constituents  of  Soil,  and  of  groicing  Vegetables. 

The  different  earths,  acids,  salts  and  organic  matters,  de- 
scribed in  this  section,  are  combined  in  the  soil  with  each 
other  in  definite  proportions.  They  are  constantly  subjected 
to  the  laws  of  affinity,  and  as  this  power  exists  in  different 
degrees  of  force  in  the  different  compounds,  there  are  frequent 
and  almost  constant  changes  going  forward.  These  changes  are 
aided  by  the  influence  of  the  atmosphere,  water,  temperature, 
etc.,  and  tend  to  alter  the  relative  proportion  of  the  different 
compounds.  The  agents  concerned  in  converting  the  rocks 
into  soils,  continue  to  act,  and  the  same  changes  continue. 
These  changes  are  those  produced  by  the  mutual  action  of 
the  organic  and  inorganic  constituents,  and  those  which  are 
produced  by  the  agency  of  the  living  vegetable. 

I.  Action  of  the  organic  and  inorganic  elements  of  soil 
upon  each  other.     The  elements  of  soil,  as  we  have  seen,  are 


ACTION  OF  THE  ELEMENTS  OF  SOIL.  219 

distributed  into  three  classes ;  silicates,  that  is  silicic  acid 
united  to  the  several  bases,  as  in  the  simple  minerals ;  salts, 
such  as  phosphates,  carbonates,  etc. ;  and  humus  or  geine, 
which  may  include  all  the  organic  portions. 

1.  The  silicates  appear  to  act  but  slightly  if  at  all  upon  each 
other,  and  hence,  were  there  no  agent  external  to  them,  would 
remain  without  change  for  ages.  But  the  carbonic  acid  of 
the  air  combines  with  the  bases  of  the  silicates,  the  potash  and 
soda,  and  forms  soluble  salts.  These  are  removed  by  water, 
and  the  silica  and  alumina  remain.  By  this  action,  the  soil 
is  rendered  gradually  and  constantly  finer,  more  clayey  and 
tenacious. 

2.  The  earthy  carbonates,  such  as  limestone,  act  in  the 
same  manner  upon  the  silicates  as  carbonic  acid,  hence  the 
utility  of  lime  to  set  the  alkalies  and  oxides  free. 

3.  The  alkaline  bases  potash,  soda,  lime,  magnesia  and 
alumina,  which  are  thus  set  free,  combine  with  the  humic, 
crenic  and  apocrenic  acids,  or,  according  to  Dana,  with  the 
geic  acid  and  form  geates,  which  are  converted  into  soluble 
super-geates,  by  the  action  of  carbonate  of  lime. 

4.  These  bases  not  only  combine  with  the  geic  acid,  but 
they  act  by  their  presence  or  catalytic  power ;  and  convert 
insoluble  into  soluble  geine.  The  power  of  hastening  decay, 
is  greatest  in  potash  and  lime,  next  in  alumina,  and  finally  in 
oxide  of  iron  while  passing  from  the  protoxide  to  the  peroxide, 
hence  the  utility  of  these  substances  in  rendering  the  vegeta- 
ble matter  soluble  and  available  to  the  roots  of  plants. 

5.  The  oxygen  of  the  air  and  of  the  water  hastens  the  pro- 
cess of  decay,  and  by  liberating  the  carbonic  acid,  tend  to 
keep  up  the  process  of  decomposition. 

II.  Mutual  action  of  growing  plants,  silicates,  salts  and 
geine.  The  action  of  salts  and  silicates  upon  each  other, 
even  when  aided  by  the  humus  of  the  soil,  is  not  very  rapid. 
But  when  a  living  plant  is  introduced  into  the  soil,  it  exerts  a 


220  GEOLOGY  AND  CHEMISTRY  OF  SOILS. 

catalytic  power,  and  causes  the  salts  and  silicates  to  form 
themselves  into  new  compounds.  Life  imparts  activity  to  all 
the  chemical  agents.  It  lets  loose  the  bases  of  the  salts  upon 
the  vegetable  matter,  and  they  convert  it  into  geine.  The 
liberated  acids  act  upon  the  silicates  and  form  new  salts, 
ready  to  be  decomposed  by  the  vital  power,  and  to  enter  the 
living  organs,  or  to  act  again  upon  the  inert  silicates  and  in- 
soluble vegetable  matter,and  render  portions  of  them  active. 
It  is  in  this  way,  that  a  small  quantity  of  salt  introduced  into 
the  soil,  will  continue  to  reproduce  itself,  and  hence  the  sur- 
prising effects  which  are  often  witnessed,  when  salts  in  small 
quantities  are  added  to  the  soil. 

1.  The  general  theory  then,  of  the  action  of  salts,  may  be 
thus  stated  :  The  bases  of  salts,  whether  alkali,  alkaline 
earth,  or  metallic  oxide,  act  exactly  alike '^  that  is,  (1)  They 
act  continually  upon  the  organic  matter  of  the  soil,  render- 
ing it  soluble  and  capable  of  entering  the  organs  of  plants. 
(2)  They  are  taken  into  the  plant,  either  in  combination 
with  their  mineral  acids,  and  decomposed  by  the  organic 
acids,  or  eliminated  directly  by  the  vital  force  and  assimilated. 
In  the  latter  case,  the  acid  of  the  salt  acts  upon  silicates  as 
above,  and  reproduces  the  same  salt. 

2.  It  will  be  seen,  that  if  the  salt  is  a  carbonate,  the  car- 
bonic acid  will  act  with  great  power  upon  the  silicates.  If  it 
is  a  phosphate  or  nitrate,  both  the  acid  and  the  alkali  are 
nourishers,  and  the  effect  will  be  much  increased.  But  if  the 
salt  is  a  sulphate,  or  a  hydrochlorate,  then  the  acid  will  not 
produce  so  good  effects,  and  may  be  poisonous  and  highly  in- 
jurious, hence  the  character  of  the  acid  determines  the  char- 
acter of  the  effect,  or,  as  it  has  been  expressed,  peculiarity  of 
action  depends  upon  the  acid  and  not  upon  the  base  of  the 
salt.  This  is  substantially  the  theory  of  Dr.  Dana.  It  throws 
more  light  on  the  action  of  salts,  than  any  which  we  have 
seen.     It  will  be  further  illustrated  on  the  subject  of  manures. 


CAUSES  OF  FERTILITY. 


221 


Sect.  4.    arcumstances  upon  which  the  Fertility   of  Soil 
depends. 

Having  in  a  previous  section,  given  the  mode  of  analysis, 
by  which  the  substances  which  have  been  described  are  ob- 
tained, this  section  will  be  devoted  to  an  examination  of  soils^ 
with  a  view  of  ascertaining,  if  possible,  the  reason  or  source 
of  their  fertility.  This  will  enable  us  to  understand  those 
various  methods  of  improvement  which  will  be  hereafter 
described. 

In  order  therefore,  to  give  ?i  practical  value  to  the  various 
topics  treated  of  in  this  chapter,  it  will  be  necessary  to  make 
some  calculations,  as  to  the  absolute  quantity  of  the  various 
ingredients  in  the  soil,  that  we  may  infer  what  the  soil  re- 
quires, as  a  condition  of  fertility.  The  first  example  which 
we  will  introduce  for  this  purpose,  is  the  analysis  by  Berze- 
lius  of  two  soils,  from  Russia  and  Siberia. 

A,  soil  never  cultivated.  B,  long  cultivated,  and  said  to 
be  in  an  exhausted  condition.     C,  sub-soil  of  the  field  B. 


f  Sand,     . 
Silica,    , 
Alumina, 
Perox.  of  iron, 
Aluminous  matter,  <[  Carbonate  of  lime 
Magnesia, 
Water, 

Phosphoric  acid, 
^  Crenic  acid, 
Acids    combined  f  Apocrenic  acid, 
with  peroxide  ofJ  ^^^ic  acid, 
iron  &  alumina,     f^^tract  of  humus, 
Humin  and  rootlets. 


A. 

1     B. 

51.84 

53.38 

17.80 

17.76 

8.90 

8.40 

5.47 

5.66 

.87 

.93 

0 

.77 

4.08 

3.75 

.46 

.46 

2.12 

1.67 

^ 

1.77 

2.34 

1.77 

.76 

•t 

3.10 

2.20 

ts. 

1.66 

1.66 

52.77 
18.65 

8.85 
5.33 
1.13 

.67 
4.04 

.46 
2.56 
1.87 
1.87 

.00 
1.66 


I  99.84  I  99.86  |  99.86 
It  will  be  seen  by  inspection  of  these  soils,  that  they  do  not 
differ  m  the  quamity  of  silica,  alumina  and  oxide  of  iron. 
The  difference  in  fertility,  therefore,  is  not  due  to  these  in- 
gredients.  Let  us  examine  further,  and  see  if  we  can  dis- 
cover the  true  cause  of  it. 

19 


222  GEOLOGY  AND  CHEMISTRY  OF  SOILS. 

The  soil  A,  which  has  never  been  cultivated  and  which 
was  the  most  fertile,  has  the  greatest  quantity  of  crenic  and 
humic  acids,  but  the  soil  B,  which  has  bfeen  exhausted,  con- 
tains less  than  1  per  cent.,  although  it  contains  a  greater 
quantity  of  apocrenic  acid  than  either.  This  acid,  however, 
and  its  salts  are  supposed  to  exert  but  little  influence  in  vege- 
tation. C,  the  sub-soil  of  B,  appears  to  have  received  nu- 
tritious matter  from  the  soil,  and  would  doubtless  yield  a  lar- 
ger crop  than  the  soil  itself.  Here,  then,  we  have  developed 
two  important  facts:  1.  That  the  fertility  of  a  soil  depends 
upon  the  humic  and  crenic  acids.  2.  That  fields  long  culti- 
vated and  almost  exhausted,  may  be  rendered  fertile  by  sub- 
soil ploughing. 

It  may  be  further  seen,  that  lime,  a  substance  essential  to 
fertility,  is  most  abundant  in  the  sub-soil,  having  been  carried 
down  from  the  soil  in  combination  with  humic  and  crenic 
acids.  This  is  another  mode  by  which  the  soil  becomes  de- 
prived of  lime  and  alkali. 

The  second  example  we  will  instance,  is  that  of  three  soils 
from  Rhode  Island,  analyzed  by  Dr.  C.  T.  Jackson. 

The  three  specimens  were  originally  of  the  same  character. 

A,  soil  in  its  natural  state,  that  would  not  produce  more  than 
10  bushels  of  corn  to  the  acre,  less  of  other  grain,  and  no  hay. 

B,  has  been  improved  by  ashing  only,  and  produces  I J  tons 
of  clover.  C,  is  in  a  high  state  of  cultivation,  and  has  pro- 
duced, in  a  three  years'  rotation,  60  bushels  of  corn,  50  of 
oats,  and  two  tons  of  hay  per  acre. 

The  coarser  pebbles  and  vegetable  fibres  were  all  taken  out 
by  sifting  the  soil  through  a  fine  sieve,  and  100  parts  of  the 
fine  materials  were  subjected  to  analysis. 

A. 

Water  of  absorption  1 .80 

Soluble  vegetable  matter  2.50 

Insoluble  vegetable  matter  2.00 

Peroxide  of  iron  2.10 

Alumina  2.10 


B. 

C. 

2.20 

1.55 

1.60 

4.60 

2.15 

1.50 

2.50 

2.07 

2.75 

1.39 

CAUSES  OF  FERTILITY.  223 


Magnesia 

1.00 

traces. 

Phosphate  and  crenate  of  lime 

1.20 

traces. 

Insoluble  silicates 

88.20 

88.20 

89.10 

99.70  100.60  100.2] 

Inspection  of  these  soils  will  show  the  cause  of  the  different 
degrees  of  fertility.  The  soil  A,  which  was  the  poorest,  con- 
tains of  soluble  vegetable  matter,  2.50  per  cent.  The  soil  B, 
next  in  fertility,  contains  1.60  per  cent.,  most  of  the  soluble 
matter  having  been  removed  by  the  agency  of  the  ashes,  with 
the  crop ;  while  the  soil  C,  in  the  highest  state  of  fertility, 
contains  4.60  per  cent,  of  soluble  vegetable  matter.  This 
alone  is  sufficient  to  account  for  their  difference.  In  fact,  in 
all  other  respects,  they  are  all  nearly  alike.  Now  this  soluble 
vegetable  matter,  is  composed  of  humic  and  crenic  acids,  or 
their  salts,  the  very  substances  which  it  is  generally  be- 
lieved are  the  nutritious  portions  of  the  soil.  On  Liebig's 
theory,  such  a  result  is  perfectly  inexplicable. 

A  third  example  is  of  two  soils  analyzed  by  Prof.  Hitchcock, 
according  to  Dr.  Dana's  rules  ;  one.  A,  from  Lazelle  county, 
Illinois,  and  never  cultivated,  and  the  other,  B,  from  Sciota 
Valley,  Ohio,  and  cultivated  14  years  without  manure. 


A. 

B. 

Soluble  geine  (humatos  and  crenates) 

7.6 

4.5 

Insoluble  geine  (humin,  etc.) 

13.8 

6.7 

Sulphate  of  lime 

18.4 

2.1 

Phosphate  of  lime 

0.4 

0.9 

Carbonate  of  lime 

3.3 

2.8 

Silicates 

73.5 

83.0 

Water  of  absorption 

9.5 

5.3 

106.1  105.3 


Both  of  these  soils  are  of  the  first  quality.  The  quantity  of 
soluble  geine  is  large,  and  also  the  amount  of  salts.  But  the 
difference  between  that  which  has  been  cultivatefl,  and  that 
which  has  not,  developes  one  of  the  most  important  facts  in 


224  GEOLOGY  AND  CHEMISTRY  OF  SOILS. 

the  whole  science  of  agricultural  chemistry  ;  a  fact,  however, 
which  has  constantly  made  its  appearance  in  these  analyses, 
viz.  that  the  quantity  of  soluble  geine  in  the  soil  A.  is  nearly 
double  of  that  in  the  soil  B,  and  the  insoluble  geine  is  more 
than  three  times  the  quantity.  What  inference  is  more  obvi- 
ous or  certain  than  this,  that  the  cultivation  of  the  soil  re- 
moves its  soluble  geine  and  favors  the  conversion  of  the  in- 
soluble portions  into  those  which  are  soluble  ;  and  that  vege- 
table matter  is  not  added*  to  the  soil  by  cultivation,  but  ab- 
stracted from  it,  and  unless  this  is  supplied,  the  land  will,  in 
time,  become  exhausted  and  consequently  barren.  Thus  it  is 
that  theoretical  deductions  confirm  actual  experience. 

These  results  are  confirmed  by  the  analysis  of  the  soils  of 
Massachusetts;  and  hence.  Dr.  Samuel  L.  Dana  of  Lowell 
has  proposed  and  advocated  a  theory  of  great  practical  im- 
portance to  the  farmer,  that  the  mineral  ingredients  of  the 
soil  are  of  little  importance,  but  that  salts  and  geine  (soluble 
vegetable  matter)  are  the  sources  of  fertility  in  all  soils.  The 
great  object  of  analysis  is  to  ascertain  the  condition  of  the 
organic  matters  in  the  soil,  and  the  means  of  improvement, 
viz.  the  conversion  of  insoluble  into  soluble  geine. 

There  are  facts  which  show,  that  alkalies  are  equally  im- 
portant with  geine,  and  the  labors  of  Dr.  Dana  and  Prof. 
Hitchcock  establish  this  fact  beyond  a  doubt.  Liebig  at- 
tributes to  the  alkalies  and  salts  a  less  extensive,  but  more 
direct  agency,  in  producing  fertility,  than  has  generally  been 
supposed. 

The  amount  of  alkalies  is  given  in  only  a  few  soils  whose 
analyses  have  fallen  under  our  notice.  But  as  the  alkalies 
are  found  in  plants,  and  exert  a  powerful  influence  in  vege- 
tation, it  may  be  interesting  to  make  some  few  calculations 
as  to  their  amount,  in  order  to  see  if  they  are  in  fact  essential 
to  fertility.     In  making  these  calculations,  we  will  give  the  ab- 

*  Unless  it  is  in  wood  lands  or  peat  meadows,  in  which  case  large 
quantities  of  vegetable  matter  are  derived  from  the  atmosphere. 


CAUSES  OF  FERTILITY.  225 

solute  amount  of  all  the  ingredients  of  an  acre  of  soil,  of  a 
tillage  depth  of  six  inches. 

In  order  to  show  distinctly  the  influence  of  alkalies  and  al- 
kaline earths,  let  us  first  estimate  the  amount,  in  a  soil  com- 
posed of  the  same  materials  as  the  rocks,  allowing  the  soil  to 
be  of  the  same  composition  as  our  ordinary  granite,  f  quartz, 
f  feldspar,  and  i  mica. 

1.  Supposing  a  cubic  foot  of  such  soil  to  weigh  125  lbs.,   1  acre 

of  tilled  surface,  6  in.  in  depth,  would  weigh  1361.25  tons. 

Of  this  there  is  of  silex  74.84  per  cent.  =     1018.76     " 

Alumina  12.80       «  174.23    " 

Potash                                            7.43       u  101.82,    " 

Magnesia                                       0.99      «  13.47    u 

Lime                                              0.37      "  5.03     « 

Oxide  of  iron                                 1.93      u  26.37    " 

Oxide  of  manganese                    0.12      "  1.63    u 

Fluoric  acid  '     ,2i       «  2  85     " 

2.  In  sienite  rock,  hornblende   takes  the  place  of  mica,  1  acre 
of  tilled  surface  6  in.  in  depth,  would  weigh  1361.25  tons. 

Of  this  there  is  of  silex  74.84  per  cent.     =     1018.76    " 

Alumina  9.79       «  ^3437     „ 

Potash  673      u  Q2.29    « 


L 


ime 


2.76      "  37.57 


Magnesia  3.76  «  57.I8 

Protoxide  of  iron  1.46  «  I9  37 

Protoxide  of  manganese  .04  "  54     u 

Fluoric  acid  .03  u  4q     » 

No  allowance  is  made  here  for  vegetable  matter,  and  the  spe- 
cific gravity  exceeds  that  of  soils  which  contain  it,  and  which 
are  in  a  finely  divided  state  and  therefore  more  bulky,  but 
the  amount  of  potash,  lime  and  magnesia  is  enormous,  com- 
pared with  the  same  substances  in  soils  which  have  been 
cultivated.  Here  is  100  tons  of  potash  on  an  acre  of  soil 
or  of  rock  six  inches  in  depth,  while  in  the  soil  of  Massachu-' 
setts,  the  fine  materials,  separated  from  the  coarse  pebbles 
accordmg  to  Prof  Hitchcock,  contain  no  potash  in  a  free 
state,  and  probably  but  a  small  quantity  in  any  state.  What 
19* 


226  GEOLOGY  AND  CHEMISTRY  OF  SOILS. 

becomes  of  this  alkali  1  We  know  that  it  enters  into  all 
vegetables,  as  it  is  found  in  their  ashes,  and  with  them  has 
been  removed  from  the  soil.  It  will  be  found  that  the  alka- 
line substajices,  limejand  magnesia,  are  also  abstracted  in  a 
similar  way,  and  hence,  as  a  practical  deduction,  soils  gene- 
rally need  to  have  these  alkalies  added,  that  their  fertility 
may  be  kept  up.  It  is  rarely  the  case,  that  the  potash  be- 
comes wholly  taken  from  the  soil,  but  it  is  locked  up  in  the 
minerals,  and  is  not  exhausted  until  they  are  all  decomposed. 
Liebig  asserts,  that  the  soils  of  Virginia,  from  which  harvests 
of  wheat  and  tobacco  were  obtained  for  a  century,  became 
exhausted,  because  their  alkalies  were  all  removed,  or  so 
large  a  quantity  of  the  free  alkali,  that  the  annual  disintegra- 
tion did  not  furnish  a  sufficient  quantity  to  supply  the  wants 
of  the  crop.  The  amount  of  alkalies,  as  estimated  per  Hes- 
sian acre,*  removed  in  the  space  of  100  years,  is  1,200  lbs. 
mostly  of  lime  and  potash.  But  generally,  the  soil  contains 
enough  potash,  locked  up  in  the  minerals,  to  answer  all  the 
wants  of  vegetation.  "  A  thousandth  part  of  loam,"  says 
Liebig,  "mixed  with  the  quartz,  in  new  red  sandstone,  or 
•with  the  lime  in  the  different  limestone  formations,  affords  as 
much  potash  to  a  soil  only  twenty  inches  in  depth,  as  is  suffi- 
cient to  supply  a  forest  of  pines,  growing  on  it  for  a  century. 
A  single  cubic  foot  of  feldspar  is  sufficient  to  supply  a  wood, 
covering  a  space  of  40,000  square  feet,  with  the  potash  re- 
quired for  five  years." 

It  would  be  easy  to  show,  that  our  forest  granitic  and 
gneiss  soils,  and  even  our  pine  plain  land,  contain  sufficient 
potash  and  lime  for  all  the  wants  of  vegetation.  But  they 
are  not  in  a  free  state,  hence,  although  growing  plants,  by 
galvanic  force,  eliminate  them  from  the  minerals,  still  they 
are  not  returned  to  the  soil  because  they  are  removed 
with  the  crop.     If  the  plants  were  all  turned  into  the  soil, 

*  A  little  less  than  an  English  acre. 


CAUSES  OF  FERTILITY.  227 

the  requisite  supply  would  be  obtained.  The  most  fertile 
soils  contain  alkalies  in  a  suitable  state  to  act,  both  upon  the 
vegetable  matter,  and  to  enter  the  vegetable  organs,  and 
hence  alkalies,  especially  potash  and  lime,  are  generally  ben- 
eficial to  the  soil. 

It  will  be  seen,  as  a  practical  inference  from  what  has  been 
stated,  that  alkalies  may  he  added  to  the  soil,  as  the  quantity 
needed  is  small.  If  it  were  required  to  add  silica ;  the  task 
of  improving  the  soil  would  be  utterly  hopeless  ;  but  a  single 
grain  of  lime  or  potash,  in  a  hundred,  is  sufficient  oftentimes 
to  ensure  fertility,  and  it  therefore  appears,  that  alkalies  as 
well  as  vegetable  matters  are  essential  to  a  fertile  soil.  This 
conclusion  may  be  rendered  still  more  evident,  by  the  follow- 
ing estimates  of  three  fertile  soils  fi-om  the  farm  of  J.  P. 
Gushing,  Esq.  Watertown,  Mass.,  in  which  the  absolute 
amount  of  the  materials  are  stated,  according  to  analysis,  by 
Dr.  C.  T.  Jackson.  The  soil  originated  from  granite,  sie- 
nite  and  greenstone. 
Insoluble  silicates  per  acre,  A.  B.  C. 

six  inches  tillage  depth      664.045  tons.  597.601  tons.  669.943  tons. 
Alumina 
Perox.  of  iron  and  mang. 

rtcJJ^,  Phos.  and  create 'of  lime 
>k  Soluable  vegetable  matter 

.  k         Insoluble  do. 

'^^i    Magnesia 
Water 

Specific  gravity 
Cubic  foot  weighs 

By  estinjates,  like  the  above,  it  is  obvious  to  any  farmer, 
that  the  salts  and  vegetable  matter  may  be  supplied  to  the 
soil,  and  that  the  great  object  of  improvement  is  to  supply 
them. 

It  has  been  stated,  that  the  mineral  ingredients  were  of 
far  less  consequence  than  it  was  formerly  supposed.  This  is 
true,  yet  it  must  not  be  inferred  that  they  are  of  no  impor- 
tance at  all. 


35.219 

(( 

30.390 

'      21.695    « 

34.494 

(( 

23.992 

'      32.976    " 

4.311 

(( 

2.399 

7.376    " 

26.733 

(( 

21.193 

'      22.562    " 

54.329 

(( 

69.177 

'      73.763    « 

1.597 

4.339    " 

39.678 

u 

43.025 

'      33.084    " 

1.277 

(( 

1.195 

1.255    " 

79.181  lbs. 

73.438  lb 

3.      79.688  lbs 

228 


GEOLOGY  AND  CHEMISTRY  OF  SOILS. 


Prof.  Hitchcock  has  shown  by  an  analysis  of  the  soils  of 
Massachusetts,  that  some  of  the  most  productive  in  the  State 
contain  less  vegetable  matter  than  those  more  barren.  Al- 
though the  proportion  of  soluble  geine,  compared  with  that 
which  is  insoluble  is  very  great,  (as  these  soils  are  the  allu- 
vial deposits  of  the  Deerfield  and  Connecticut  rivers,)  it  is 
chiefly  the  frie  state  of  the  mineral  ingredients  which  will 
account  for  their  fertility.  They  must  be  exhausted  much 
sooner  than  other  less  fertile  soils,  and  will  of  course  require 
a  constant  supply  of  vegetable  matter,  to  keep  up  their  fer- 
tility. 

A  continued  course  of  cropping  improves  the  texture  of 
nearly  all  soils.  They  gradually  become  finer,  and  must  be 
deepened  to  supply  the  requisite  quantity  of  decomposable 
minerals. 

We  will  close  this  subject,  by  a  general  summary  of  the 
principles  which  have  been  developed,  considered  in  their 
practical  relations  to  our  soils. 

1.  The  first  general  conclusion  is,  that  it  is  important  to 
the  farmer  to  obtain  an  exact  knowledge  of  the  ingredients 
of  his  soil,  in  order  to  make  the  required  improvement.  If 
a  soil  is  not  productive,  analysis  will  show  the  reason,  and 
point  out  the  right  mode  of  securing  fertility. 

2.  Although  the  mineral  ingredients  of  a  soil  are  far  less 
important  than  the  humus  and  salts,  yet  it  is  well  established, 
that  a  soil  composed  wholly  or  ^^  of  s'ilica,  lime,  alumina  or 
magnesia,  is  entirely  barren,  hence  sand  or  clay  will  not  sup- 
port vegetation. 

3.  Two  kinds  of  earth  are  necessary  to  the  fertility  of  any 
soil,  viz.  silica  and  alumina.  But  a  soil  does  not  attain  its 
highest  degree  of  fertility,  unless  there  are  added  small  quan- 
tities of  lime,  magnesia,  oxide  of  iron  and  of  manganese.  At 
least,  three  earths  are  essential  to  the  highest  state  of  fertility. 
Plants  require  but  a  small  quantity  of  these  earths  to  enter  in- 
to their  constitution,   therefore  the   proportions   may   vary 


CAUSES  OF  FERTILITY.  229 

widely  without  any  apparent  effect,  provided  the  texture  be 
continued  the  same. 

4.  The  fineness  of  the  earthy  ingredients  is  more  impor- 
tant to  fertility,  than  the  proportions  in  which  they  exist ;  be- 
cause the  power  of  the  soil  to  absorb  water,  and  of  the  roots 
of  plants  to  draw  in  nourishment,  depend  upon  the  fineness 
of  the  particles  ;  hence  it  is  found,  that  one  earthy  ingredient 
may  be  substituted  for  another,  provided  the  electrical  char- 
acter of  the  soil  is  not  changed.  If,  however,  we  are  sure 
that  a  soil  contains  silica,  alumina,  lime  and  oxide  of  iron, 
it  may  be  made  fertile.  We  are  sure  of  all  but  the  lime, 
which  exists  in  a  small  quantity  in  all  our  soils,  and  may  be 
added  generally  without  fear  of  injury. 

5.  But  the  most  important  substances  to  be  attended  to 
are  vegetable  matters  and  salts.  Without  these,  soils  are  ab- 
solutely barren,  however  well  constituted  in  their  mineral 
portions. 

6.  Fertility  depends  not  upon  the  quantity  of  humus,  but 
upon  its  state.  The  greater  the  quantity  of  soluble  geine 
(humates,  crenates  and  apocrenates),  other  things  being  equal, 
the  greater  the  fertility. 

7.  As  salts  are  removed  by  continued  cropping,  they  must 
be  supplied  from  the  rocks,  or  from  a  foreign  source;  hence 
their  utility  as  a  manure. 

8.  It  may  be  inferred,  that  the  best  constituted  soil  contains 
the  various  ingredients  in  about  the  following  proportions : 
silica  60  parts  in  100,  alumina  16,  lime  3,  oxide  of  iron  and 
manganese  7,  soluble  geine  4,  insoluble  geine  5,  potash  3, 
soda  1,  magnesia  1.  The  earthy  constituents  may  vary,  but 
the  salts  and  geine  must  be  from  4  to  10  per  cent.,  or  the  soil 
will  not  produce  a  bountiful  crop. 

9.  Finally,  those  substances  which  our  soils  require  to  en- 
sure fertility,  are  within  the  reach  of  all  our  farmers,  and  there 
is  the  best  encouragement  for  all  to  seek  them  out  and  apply 
them.      No  excuse  can  be  rendered  if  their  farms  do  not 


230 


GEOLOGY  AND  CHEMISTRY    OF  SOILS. 


produce  bountifully,   if  their  own  stores  are  not  well  sup- 
plied with  all  the  necessaries  and  comforts  of  life. 

Sect.  5.   Classification  and  Description  of  Soils. 

As  all  soils  originate  from  the  decomposition  and  disinte- 
gration of  rocks,  effected  by  the  chemical  >and  mechanical 
agency  of  air,  water,  and  vegetation,  to  which  small  quanti- 
ties of  vegetable  and  animal  matters  are  added,  the  most  ob- 
vious mode  of  classification  would  seem  to  be  that  derived 
from  the  geological  character  of  the  rocks.  For  we  should 
expect  that  soils  would  resemble  the  rocks  from  which  they 
originated,  and  (with  the  exception  of  some  cases  of  great  dis- 
turbance by  glacial  action,  or  running  water,  in  which  cases 
several  varieties  of  rock  are  mingled  together),  that  the  rock 
from  which  the  soil  originated  would  underlay  it.*  The  fact 
too  that  we  must  look  to  geology,  to  ascertain  those  natural 
sources  of  fertility,  which  are  so  abundant  and  desirable  in 
every  country,  renders  some  knowledge  of  this  science  abso- 

*  Dr.  Dana  in  his  Muck  Manual,  p.  20,  has  given  as  the  third  prin- 
ciple of  agricultural  chemistry,  that  "  the  rocks  have  not  formed  the 
soil  which  covers  them."  This  appears  to  be  true  in  a  restricted  and 
modified  sense.  The  soil  has  been  moved  in  most  cases  from  the  rock 
in  place,  but  not  alwaj'^s  beyond  the  formation.  There  are  many 
cases,  where  the  soil  is  found  to  have  originated  directly  from  the  de- 
cay of  the  underlaying  rock.  The  second  principle,  "  that  rocks  do 
not  affect  the  vegetation  which  covers  them,"  p.  11,  seems  to  require 
a  similar  modification.  There  are  many  exceptions  to  the  rule,  and 
the  truth  would  be  as  nearly  expressed  if  the  negative  were  left  out. 
A  case  now  occurs  to  me  of  the  marked  influence  of  the  underlaying 
rock.  There  is  a  small  belt  of  land  in  the  southern  part  of  Vermont, 
in  which  one  ingredient  is  silicate  of  lime,  and  the  vegetation  is  not 
only  more  flourishing  in  this  formation,  but  the  sweet  grasses  as  clover 
are  much  more  abundant,  although  the  situation  is  high,  and  it  is 
otherwise  more  unfavorable  than  the  neighboring  soils,  which  are  less 
fertile.  Hence,  the  first  principle,  that  "  there  is  one  rock  and  conse- 
quently one  soil,"  appears  to  be  opposed,  not  only  to  the  general  opin- 
ion of  writers  on  soils,  but  to  direct  observation. 


CLASSIFICATION  AND  DESCRIPTION  OF  SOILS.  231 

lutely  essential  to  an  intelligent  understanding  and  success- 
ful practice  of  agriculture  as  an  art. 

But  as  such  a  classification  may  not  be  intelligible  to  those 
who  are  wholly  ignorant  of  geology,  the  more  common  clas- 
sification of  agricultural  writers  is  added,  in  which  no  refer- 
ence is  had  to  the  geological  origin,  but  only  to  the  chemical 
character  of  the  soil.  It  will  be  seen  that  both  modes  corres- 
pond in  many  important  particulars,  and  it  is  hoped,  that  the 
infinite  importance  of  an  exact  knowledge  of  soils  to  the  prac- 
tical farmer,  will  be  a  sufficient  apology  for  adopting  a  method 
which  must  necessarily  lead  to  some  degree  of  repetition. 
Perhaps  we  ought  to  urge  this  as  a  peculiar  excellence,  inas- 
much as  each  mode  will  throw  light  upon  the  other,  and  en- 
able the  careful  student  to  obtain  a  clearer  and  more  com- 
prehensive view  of  the  subject,  than  either  mode  taken  by  it- 
self. 

Geological  Classification  and  Description  of  Soils. 

Geologists  make  two  general  divisions  of  the  rocks : 
1.  Stratified,  or  those  rocks  which  are  found  in  regular  lay- 
ers, like  the  leaves  of  a  book,  and  which  appear  to  have  been 
deposited  from  a  mechanical  and  chemical  suspension  in  wa- 
ter. 2.  Unstratified,  or  those  which  have  no  marks  of  strata, 
but  appear,  from  their  texture  and  resemblance  to  the  lava  of 
volcanoes,  to  have  once  been  in  a  fused  or  melted  state.  The 
stratified  rocks  are  divided  into  Aluvium,  Diluvium  or  Drift, 
Tertiary,  Secondary  and  Primary.  Each  of  these  divisions 
are  variously  subdivided.  The  chemical  distinction  was 
pointed  out  page  187.  Geologically,  then,  soils  may  be  di- 
vided into  the  five  following  classes  :  Alluvial,  Diluvial,  Ter- 
tiary, Secondary  and  Primary  soils. 

I.  Alluvial  soils.  These  are  of  two  kinds  ;  those  formed 
by  rivers,  and  those  resulting  from  peat-swamps,  or  growing 
vegetables. 

1.  Alluvial  soil  of  rivers  consist  of  particles  of  every  kind 


232 


GEOLOGY  AND  CHEMISTRY  OF  SOILS. 


of  rock,  over  which  the  stream  passes.  The  water  suspends 
large  quantities  of  matter,  which,  in  connection  with  the 
mineral  ingredients,  is  composed  of  various  vegetable  sub- 
stances. This  is  deposited  at  the  mouths  of  rivers,  or,  when 
they  overflow  their  banks,  along  their  margins.  This  soil 
will  be  fertile  or  barren  according  to  the  character  of  the 
rock  over  which  the  rivers  flow.  Alluvial  soil  is  generally  the 
most  fertile  and  desirable  of  all  soils.  It  appears  to  owe  its 
fertility  to  the  fine  state  of  its  particles,  or  to  its  tex- 
ture, and  the  condition  of  its  vegetable  constituents.  For  it 
is  found,  by  analysis,  to  contain  less  of  vegetable  food  than 
most  other  soils.  But  when  rivers  pass  over  sandstones,  it 
often  happens,  that  no  vegetable  matter  is  intermingled,  and 
instead  of  fertility,  nothing  being  washed  down  but  silicious 
matter,  we  have  heaps  of  barren  sand.  Most  of  the  alluvial 
soils  of  New  England  and  of  the  Western  States  are  fertile  ; 
while  many  along  the  coast  of  the  Southern  States  are  bar- 
ren plains. 

The  value  of  alluvial  soil  depends  upon  another  circum- 
stance. If  the  sub-soil  is  gravelly  or  sandy,  the  water,  and 
with  it,  the  manure  passes  down  below  the  soil  into  the  sub- 
soil. This  kind  of  soil  is  the  most  easily  recognized  of  any  ; 
and  every  farmer  knows  it,  under  the  name  of  interval  or 
meadow  land.  Its  position  also  points  it  out,  as  it  is  gen- 
erally found  along  the  banks  of  rivers,  and  at  their  mouths. 
In  the  latter  case,  the  ocean  waves  often  throw  it  back  mix- 
ed with  marine  exuvia  upon  the  land,  and  form  salt-marsh  al- 
luvions. The  valley  of  the  Connecticut  river  in  New  Eng- 
land, presents  some  fine  examples  of  river  alluvium  ;  for  ex- 
ample, the  meadows  of  Deerfield,  Hadley,  Northampton,  etc. 
But  alluvial  soils  are  much  more  extensive  in  the  Middle  and 
Western  States,  especially  in  the  vallies  of  the  Mohawk, 
Ohio,  Mississippi  and  Missouri.  In  the  West,  it  has  receiv- 
ed the  name  of  bottom  land. 

2.  Peat  alluvial  soils.     Among  the   alluvial  soils  n)ay  be 


DILUVIAL  OR  GLACIAL  SOILS.  233 

ranked  the  pmty  soils,  which  consist  mostly  of  vegetable 
matter,  partly  decayed  and  partly  in  a  state  of  preservation. 
This  variety  of  soil  is  of  every  degree  of  texture  and  fertility. 
Some  of  the  peat  meadows  and  swamps  contain  pure  peat, 
with  a  small  quantity  of  mineral  matter.  In  this  case, 
they  should  be  regarded  rather  as  depositories  of  fuel  and  ma- 
nure. But  they  can  be  made  the  most  valuable  of  all  soils, 
because  they  contain  inexhaustible  quantities  of  vegetable 
food. 

Peaty  soils,  include  all  those  in  which  are  found  large 
quantities  of  vegetable  matter,  in  a  partially  decomposed  state. 
A  large  portion  of  the  peaty  soils  are  left  wholly  barren, 
through  want  of  chemical  skill  to  bring  them  into  the  proper 
state  for  producing  crops. 

11.  Diluvial  or  glacial  soils.*  These  are  more  extensive 
than  any  other.  They  seem  to  have  resulted  from  the  action 
of  glaciers,  when  the  position  of  the  earth  was  different  from 
what  it  is  at  present.  They  are  composed  of  sand,  gravel 
and  rounded  pebbles,  which  are  mingled  together  and  appear 
to  have  been  moved,  in  a  southerly  direction  from  the  rock 
out  of  which  they  were  formed.  In  consequence  of  this  trans- 
portation of  the  abraded  materials,  by  glacial  or  some  other 
action,  the  detritus  of  several  kinds  of  rock  are  in  some  cases 
commingled.  In  others,  the  materials  are  not  carried  far  be- 
yond the  rock  from  which  they  were  formed  ;  so  that  the  ex- 
tent of  this  division  of  soils  is  much  less,  than  would  other- 
wise appear. 

Diluvial  soils  may  be  divided  into  three  varieties ;  sandy, 
gravelly  and  argillaceous. 

1.  The  sandy  and  gravelly  diluvial  soils  differ  only  in  the 
relative  fineness  of  their  materials.  The  most  common  varie- 
ties consist  of  course  sand,  and  rounded  pebbles.     These  are 

"  Called  glacial  soils  because  it  is  now  pretty  well  established,  that 
the  diluvial  or  drift  was  formed  by  glaciers.  (See  Hitchcock's  Report 
of  the  Geology  of  Massachusetts.) 

20 


234  GEOLOGY  AND  CHEMISTRY  OF  SOILS. 

the  poorest  of  soils,  especially  when  the  pebbles  and  the  sand 
are  mostly  from  quartz  rock.  They  form,  to  a  great  extent 
the  silicrous  soils  of  agricultural  writers,  and  are  generally 
warm  and  dry,  without  the  power  of  retaining  the  manures 
which  are  placed  upon  them. 

2.  The  other  variety  of  the  diluvial  soils,  the  argillaceous, 
are  exactly  similar  to  those  in  the  next  class.  They  are 
formed  of  clay  and  sand,  and  are  the  opposite  of  the  gravelly 
diluvial  soils  in  their  character,  being  heavy,  moist,  retentive 
of  manures,  and  of  water.  They  are  capable,  however,  of 
being  made  the  most  fertile  and  valuable  of  soils ;  as  they 
compose  what  are  generally  denominated  clayey,  and  when 
long  cultivated,  loamy  soils. 

III.  Tertiary  soils.  The  tertiary  rocks  are  alternate  beds 
of  sand,  clay  and  marl,  generally  arranged  in  horizontal  lay- 
ers, and  often  not  hardened  into  solid  rock.  The  clays  or  argil- 
laceous earths  seem  to  have  originated  from  the  argillaceous 
minerals ;  of  which  feldspar,  mica  and  zeolite  are  the  prin- 
cipal. These,  with  the  last  described  variety  of  the  diluvial 
soil,  answer  to  the  description  of  clayey  soils,  although  soils 
from  the  tertiary  rocks  include  several  varieties.  The  cagil- 
laceoiis  in  which  clay  predominates,  and  the  sandy  which  re- 
semble the  soils  of  the  diluvium,  are  two  important  divisions. 

The  tertiary  beds,  many  of  them,  seem  to  have  resulted 
from  the  filling  up  of  ponds  and  lakes  which  were  sometimes 
covered  with  fresh,  and  at  others,  with  salt  water;  hence, 
they  are  often  composed  mostly  of  carbonate  of  lime,  and 
are  filled  with  fossil  remains,  especially  of  shell  fish.  But 
the  more  common  variety  of  this  soil  is  the  clayey,  and  this 
varies  from  the  stiff  clays  in  which  water  and  manures  are  re- 
tained for  a  long  time,  and  which  are  generally  cold,  wet  and 
unfruitful,  to  i\\e  richest  clay  loams,  in  which  there  is  just  sulfi- 
cient  alumina  to  give  them  body,  and  to  enable  them  to  sup- 
port the  roots  of  the  grains  and  grasses,  for  which  crops  they 
seem  best  fitted. 


TERTIARY  AND  SECONDARY    SOILS.  235 

The  sandy  varieties  of  the  tertiary  soil  often  consist  of  al- 
most pure  sand,  laying  directly  upon  beds  of  clay.  They 
may  be  easily  improved  by  deep  ploughing,  especially  when 
the  clay  is  not  more  than  6  or  10  inches  below  the  surface. 
The  sand  and  clay  being  mingled  together,  will  improve  the 
texture.  The  clay  often  contains  carbonate  of  lime  and  ox- 
ide of  iron  ;  two  indispensable  substances  to  the  fertility  of 
any  soil.  But  as  most  of  the  tertiary  soils  resemble  those 
from  other  formations,  they  will  be  described  under  the  head 
o^  clayey  soils. 

The  tertiary  soil  is  of  limited  extent  in  New  England.  It 
is  confined  mostly  to  the  region  of  plastic  clay.  All  the  com- 
mon clay-beds,  and  the  soils  resulting,  are  assigned  by  Prof. 
Hitchcock  to  the  diluvium. 

IV.  Secondary  soils  or  soils  from  the  secondary  rocks. 
The  secondary  formation  includes  a  great  variety  of  rock,  and 
consequently  a  similar  variety  of  soil.  It  would  be  useless 
here  to  point  out  all  these  varieties,  as  the  chemical  mode  of 
classification  will  bring  many  of  them  together,  as  identical 
in  composition,  and  in  their  agricultural  relations. 

1.  The  cretaceous  or  chcdky  soil  is  rarely  found  in  this 
country,  but  is  very  abundant  in  England.  (1)  It  consists  of 
calcareous  earth  in  the  form  of  chalk  or  marl,  mingled  with 
flint,  pebbles  or  concretions,  and  will  be  described  under  the 
head  calcareous  soil.  When  this  soil  covers  chalk  rocks  it 
is  white,  and  reflects  the  heat,  hence  it  is  often  cold  ;  but 
many  varieties  of  it  are  very  fertile. 

(2)  A  second  variety  of  the  cretaceous  soil  consists  partly 
of  green  sand,  resembling  chlorite  or  green  earth  mingled 
with  sand.  The  green  sand  often  contains  large  quantities  of 
potash,  and  has  been  used  in  New  Jersey  as  a  manure  with 
the  most  salutary  effects.  But  this  variety  of  soil,  in  this 
country,  with  the  exception  of  New  Jersey,  does  not  gene- 
rally contain  potash. 

(3)  A  third  variety  consists  of  blue  marl  clay,  carbonate 


236  GEOLOGY  AND  CHEMISTRY  OF  SOILS. 

of  lime,  with  sand  and  fossil  shells,  which  are  derived  mostly 
from  the  gault  or  wealden  rocks.  These  resemble  the  clayey 
soils  of  the  tertiary  formation. 

2.  Oolitic  soil  is  remarkable  for  the  quantity  of  calcare- 
ous earths  which  it  contains.  It  is  derived  from  argillaceous 
limestones,  clays  and  marls,  and  in  consequence  of  the  great 
quantity  of  fossil  remains,  is  a  very  fertile  soil. 

3.  Salifcrous  or  sanchtone  soil  is  derived  from  sandstone 
rocks.  It  is  composed  of  argillaceous,  siliceous  or  calcareous 
matters,  often  highly  charged  with  red  oxide  of  iron,  which 
gives  to  the  soil  a  red  appearance.  It  is,  however,  of  every 
shade  of  color,  and  variety  of  texture  and  composition,  vary- 
ing from  light  sandy  loams  to  stiff  marly  clays.  The  sand- 
stone soil  of  New  England  is  either  colored  red  as  in  the 
valley  of  the  Connecticut  river,  or  gray.  It  is  warm,  dry  and 
capable  of  being  made  very  fertile.  The  rocks  from  which 
this  soil  is  derived  often  contain  gypsum  and  common  salt,  as 
at  Salina,  New  York,  and  on  this  account  favor  the  growth  of 
those  plants  which  require  a  large  quantity  of  soda.  Ow- 
ing to  its  texture,  it  is  particularly  favorable  to  Indian  corn, 
and  the  tap-roots,  beets,  carrots  and  turnips.  The  magnesian 
variety  is  much  more  retentive  of  water,  and  constitutes  a 
very  fertile  soil. 

4.  Carboniferous  soil  is  derived  from  three  kinds  of  rock. 
1.  Thq  shales  of  the  coal  beds,  consisting  mostly  of  argilla- 
ceous earth  with  vegetable  remains  and  sandstones.  2.  Car- 
boniferous limestone,  also  called  mountain  limestone,  which 
is  so  filled  with  the  remains  of  small  animals,  Enchrinites,  as 
to  receive  the  name  of  enchrinal  limestone.  3.  The  old  red 
sandstone,  which  does  not  differ  essentially  from  the  red  sand- 
stone of  the  preceeding  class.  The  soil  will  of  course  vary 
with  the  kind  of  rock. 

5.  Silurian  or  grat/iaackc  soil  oug\n:ites  from  an  extensive 
class  of  rocks,  under  the  name  of  graywacke,  graywacke 
slate  and  shale.     It  is  composed  of  sand,  clay  and  calcare- 


PRIMARY  SOILS.  237 

ous  matter.     The  following  are  the  principal  varieties  of  this 
soil. 

( 1 )  The  conglomerate  soil,  consisting  mostly  of  coarse  sand 
and  pebbles  which  have  been  once  cemented  together,  but 
are  now  crumbled  into  soil.  The  rock  is  known  as  pudding 
stone  and  is  found  in  Roxbury,  Dorchester,  and  many  other 
places  in  the  eastern  part  of  Massachusetts.  It  is  far  the 
best  soil  found  in  this  class. 

(2)  Slati/  soil,  of  a  gray  color,  more  retentive  of  moisture 
and  often  clayey,  but  capable  of  being  made  very  fertile. 

(3)  Slati/  red  soil,  in  which  the  rock  and  the  soil  is  of 
a  deep  chocolate ;  in  other  respects  it  does  not  differ  from 
the  preceding.  Sometimes  these  three  kinds  are  mingled 
together,  and  when  the  coarse  pebbles  constitute  the  sub-soil, 
it  is  often  subject  to  suffer  by  drought  and  to  permit  the  ma- 
nures to  pass  through,  without  producing  much  effect  upon 
the  crop. 

As  the  coal  measures  repose  upon  the  graywacke,  it  of- 
ten happens  that  the  fine  graywacke  soil  becomes  mingled 
with  the  carbonaceous  clay  slate,  which  renders  the  soil  of  a 
clayey  texture. 

4.  Claj/  slate  soil.  This  soil  is  similar  to  the  preceding, 
but  generally  finer  in  texture  and  more  argillaceous  or  clay- 
ey. It  is  the  oldest  of  the  secondary  soilsj  and  contains  but 
few  remains  of  plants  or  animals.  The  carbonaceous  clay 
slate  rocks  when  mixed  with  graywacke  make  a  very  fertile 
soil.  It  is  black,  retentive  of  moisture,  and  well  adapted  to 
grain,  herdsgrass  and  clover.* 

V.  Primary  soils,  or  soils  from  the  primary  stratijied  and 
unstraiijied  rocks.  This  division  includes  a  great  variety  of 
soils.  The  most  common  variety  in  New  England,  are  ar- 
gillaceous slate,  limestone,  mica  slate,  talcose  slate,  gneiss, 
granite,  sienite  and  porphyry  soils.  The  trappean  varieties 
form  a  distinct  class. 

*  See  Jackson's  Report  of  Geology  of  Rhode  Island,  p.  127. 
20* 


238  GEOLOGY   AND  CHEMISTRY    OF   SOILS. 

Soils  from  tlie  primary  rocks  are  most  abundant  in  New 
England.  They  are  derived  mostly  from  the  decomposition 
or  decay  of  granite,  gneiss,  mica  slate,  argillaceous,  talcose, 
and  hornblende  slates.  These  rocks  contain  the  ingredients 
of  nearly  all  soils ;  silica,  alumina,  lime,  magnesia,  oxide  of 
iron  and  of  manganese,  to  which  may  be  added  the  alkalies, 
potassa  and  soda.  They  are  generally  distinguished  by  the 
minerals  which  they  contain,  and  which  exist  either  in  large 
or  fine  particles.  The  principal  minerals  are  mica,  feldspar 
and  quartz.  The  mica  is  seen  in  thin  shining  scales  ;  the 
quartz  in  angular  or  rounded  pebbles,  and  the  feldspar  in 
white  and  earthy  particles,  more  or  less  covered  with  oxide 
of  iron,  or  vegetable  mould.  These  ingredients  may  be  de- 
tected by  mixing  the  soil  in  water,  agitating  it  a  while,  and 
pouring  off  the  finer  portions. 

1.  Argillaceous  slate  soil  is  derived  from  a  rock  well 
known  from  its  structure,  and  from  its  use  for  the  purpose  of 
roofing  buildings.  It  exists  in  very  great  perfection  in  Ber- 
nardstown,  Mass.  and  Guildford,  Vt.  The  color  of  this  soil 
resembles  the  slate,  which  is  dark  brown,  almost  black.  It 
is  a  poor  soil  in  many  places,  especially  where  the  rock  ap- 
proaches near  the  surface,  but  when  the  disintegration  has 
proceeded  to  a  greater  depth,  it  is  capable  of  being  made  a 
very  good  soil.  It  is  composed  almost  entirely  of  argillace- 
ous earth,  mixed  with  a  small  quantity  of  silex. 

2.  Limestone  soil.  The  primitive  limestones  which  are 
interstratified  with  the  slates,  give  rise  to  a  variety  of  soil, 
which  does  not  differ  materially  from  the  talcose  and  mica 
slate  soil,  as  it  appears  from  analysis,  that  some  of  them  do 
not  contain  carbonate  of  lime  in  any  considerable  quantities. 
This  may  be  due  to  the  action  of  crops,  or  to  the  fact  that 
the  detritus  of  other  rocks  have  been  brought  over  them,  and 
constitute  their  principal  mass. 

Some  varieties  of  this  soil  contain  carbonate  of  lime,  others 


PRIMARY  SOILS.  239 

carbonate  of  lime  and  magnesia,  forming  the  magnesian  lime- 
stone soil.  A  third  variety  contains  feruginous  limestone, 
or  iron  combined  with  the  lime,  and  the  fourth  variety  con- 
tains silex  or  siliceous  carbonate  of  lime.  This  latter  soil  is 
very  fertile,  and  yields  very  sweet  food  for  grazing. 

The  primary  limestones  diifer  from  the  secondary  in  be- 
ing less  friable  and  in  containing  no  organic  remains. 

The  magnesian  variety  from  both  the  secondary  and  primary 
rocks  is  highly  fertile,  for  although  magnesia,  in  its  caustic 
state,  appears  to  be  injurious  to  vegetation,  the  rock  itself, 
when  crumbled  into  soil,  exerts  no  such  effects ;  probably 
because  it  is  already  combined  with  carbonic  acid. 

The  best  test  of  a  limestone  soil  whatever  be  its  origin,  is 
any  dilute  acid  such  as  the  sulphuric,  in  which  case,  the  car- 
bonic acid  will  escape  with  effervescence  or  with  foam,  when 
the  soil  is  put  into  water,  and  the  acid  poured  upon  it. 

The  calcareous  or  limestone  soil  is  of  every  degree  of  fer- 
tility, and  is  best  fitted  for  wheat,  clover  and  the  sweet  gras- 
ses. 

3.  3Iica  slate  soil,  like  the  rock,  is  composed  mostly  of  mi- 
ca and  quartz.  It  is  distinguished  from  clay  slate  soil,  by 
its  lighter  color,  yet  these  two  rocks  frequently  pass  into  each 
other,  and  of  course  the  soils  are  also  mingled.  In  some 
cases  the  mica  slate  passes  into  gneiss  and  argillaceous  slate, 
and  the  soil  of  course  will  partake  of  the  character  of  both 
rocks.  This  soil  is  found  in  very  many  places  in  Worcester 
county,  Mass.  and  in  all  the  New  England  States,  and  is 
generally  very  fertile.  It  contains  but  little  feldspar,  and 
hence  but  little  potash,  but  the  mica  yields  a  large  quantity 
of  magnesia,  which  gives  it  an  adhesive  and  loamy  character. 

4.  Talcose  slate  soil  can  hardly  be  distinguished  from  the 
mica  slate  by  its  color,  although  it  is  somewhat  lighter.  It 
contains  talc  instead  of  7nica,  and  these  may  be  easily  distin- 
guished ;  the  former  is  non-elastic  and  of  a  soapy  feel,  the 
latter  elastic  and  tough. 


240  GEOLOGY  AND  CHEMISTRY  OF  SOILS. 

The  fertility  of  this  soil  depends  upon  the  mixture  of  oth- 
er earths,  such  as  clay.  The  argillaceous  slate  soil  is  quite 
productive,  but  generally  this  soil  is  more  sandy  and  less  fer- 
tile than  that  from  mica  slate. 

5.  Gneiss  soil  is  very  abundant  in  New  England.  It  has  a 
pale  yellow  color,  and  is  sandy  and  gravelly,  indicating  by 
its  appearance  great  sterility.  This,  however,  is  not  always 
the  case  ;  the  gneiss  rocks  contain  large  quantities  of  potash 
in  their  feldspar,  as  well  as  argillaceous  and  siliceous  sub- 
stances. These  minerals  when  reduced  to  the  proper  de- 
gree of  fineness  make  a  very  fertile  soil.  It  is  of  two  kinds, 
the  common  and  the  ferruginous  gneiss  soil.  The  latter  is  of 
a  reddish  color,  in  consequence  of  the  peroxide  of  iron  which 
it  contains. 

6.  Granite  soil  does  not  differ  essentially  from  gneiss.  Both 
are  composed  of  quartz,  feldspar  and  mica,  and  of  course 
yield  all  the  mineral  materials  necessary  to  fertility.  The 
granite  soil  differs  in  its  texture  from  coarse  gravel  to  fine 
sand.  Dr.  Dana  regards  all  soils  as  composed  essentially  of 
"  granitic  sand,"  that  is,  just  such  materials  as  granite  and 
gneiss  rocks  would  produce  by  the  ordinary  process  of  disin- 
tegration. These  rocks  yield  all  the  earths  necessary  to  the 
highest  degree  of  fertility.  But  their  degree  of  fertility  will 
depend  upon  their  texture  and  the  sub-soil.  When  they  are 
underlaid  with  clay,  or  hard  gravel,  cemented  together  and 
made  water-tight,  they  may  be  made  very  fertile,  because  they 
will  then  retain  the  soluble  manures ;  but  if  the  substratum  is 
open  gravel  or  sand,  the  soil  itself  gravelly  or  sandy,  they  are 
too  easily  drained  of  moisture,  and  permit  the  soluble  ma- 
nures to  infiltrate  or  leach  throuo-h  them.  Gneiss  and  granitic 
soils  are  better  for  Indian  corn  and  grass  than  for  the  smaller 
grains. 

7.  Sienite  soil  differs  from  granite  in  containing  horn- 
blende instead  of  mica.     Its  structure  is  somewhat  finer,  and 


TRAPPEAN  SOILS.  241 

its  color  darker  than  either  of  the  preceding.    It  is  also  warmer 
and  more  favorable  to  cultivation. 

8.  Hornhlcndc  rock  soil.  Hornblende  rock  is  composed 
chiefly  of  hornblende  and  compact  feldspar,  with  variable 
portions  of  oxide  of  iron  and  of  manganese,  and  the  soil  is 
composed  of  similar  materials.  The  color  is  generally  of  a 
dark  red-brown,  of  a  fine  texture,  slightly  adhesive  when 
pressed  in  the  hand,  but  not  clayey.  This  soil  contains  a 
large  quantity  of  oxide  of  iron,  manganese  and  magnesia,  the 
latter  substance  supplies  the  place  of  clay ;  the  manganese, 
from  its  dark  color  and  imperfect  conducting  power,  renders 
the  soil  warm  and  highly  fertile. 

9.  Porphyry  soil  is  derived  from  the  compact  feldspars, 
which  contain  from  25  to  30  per  cent,  of  alumina.  The  por- 
phyry rock  is  among  the  hardest,  but  it  yields  rapidly  to  the 
agents  of  disintegration,  and  forms  a  very  valuable  soil. 

VI.  Trappean  soils  differ  from  the  preceding  by  contain- 
ing from  3  to  7  per  cent,  more  of  lime,  magnesia  and  iron,  and 
20  per  cent,  less  of  silex. 

1.  Greenstone  soil  is  often  associated  with  porphyry.  It 
is  of  a  finer  material,  and  more  fertile.  The  character  of 
these  soils  is  often  distinct,  of  a  brown  color,  containing  large 
quantities  of  iron.  Basaltic  soil  is  very  similar  to  the  above, 
but  it  is  composed  of  augite  and  feldspar. 

2.  Trachyte  soil.  This  is  the  soil  from  the  ancient  lava, 
and  is  found  around  volcanoes.  It  contains  a  large  quantity 
of  alkalies,  which  make  it  highly  fertile.  It  is  composed  of 
glassy  feldspar,  hornblende,  mica,  titaniferous  iron,  and  some- 
times augite. 

3.  Lava  soil.  The  more  recent  lava,  when  converted  in- 
to soil,  is  often  very  fertile.  It  contains  so  large  quantities  of 
alkali,  such  as  potash,  soda,  etc.  that  for  some  crops,  it  is  the 
best  of  all  soils.  The  two  minerals,  feldspar  and  augite,  con- 
stitute nearly  the  entire  mass  of  this  soil.     As  these  matters 


242  GEOLOGY  AND  CHEMISTRY  OF  SOILS. 

are  subjected  to  heat,  there  is  a  partial  decomposition,  and  the 
alkalies  are  ready  to  act  upon  the  crop. 

The  above  enumeration  contains  the  most  important  varie- 
ties of  soil  as  derived  from  the  rocks.  They  will  be  readily 
recognized  by  the  practical  geologist,  and  it  is  hoped  that  the 
farmer  may  derive  some  idea  of  their  character  and  proper- 
ties. 

This  geological  classification,  which  is  based  chiefly  on  that 
proposed  by  Prof  Hitchcock,  makes  us  acquainted  with  the 
soils  as  they  stand  related  to  the  rocks.  This  is  always  use- 
ful and  interesting,  especially  to  the  scientific  agriculturist ; 
but  it  is  not  so  practical  as  the  chemical  mode  of  classifica- 
tion. It  is  to  be  hoped  that  the  reader  will,  at  least,  examine 
this  method  and  compare  it  with  that  which  follows,  that  he 
may,  as  already  remarked,  obtain  from  both  what  could  not 
be  derived  from  either  by  itself. 

II.   Chemical  Classijication  and  Dcsci-iption  of  Soils. 

We  regard  the  geological  classification  of  soils,  as  pre- 
senting the  most  enlarged  view  of  the  subject;  but  a  more 
simple  and  practical  method  is  to  arrange  soils  according  to 
their  prevailing  earths.  These  earths  are  silica,  alumina, 
lime  and  magnesia.  Hence  those  soils  in  which  silex  niostly 
predominates,  are  called  siliceous  or  sandy  soils.  Those  in 
which  clay  is  in  the  greater  proportion,  are  called  aluminous 
or  clayey  soils.  Those  in  which  the  carbonate  of  lime  is  the 
chief  ingredient,  calcareous  soils ;  and  when  the  lime  is  chalk, 
chcdky  soils.  Magnesia,  also,  sometimes  exists  in  sufficient 
quantities  to  give  a  name  to  the  soil  in  which  it  is  found. 
There  is  another  class  called  loamy,  which  answers  nearly  to 
the  more  fertile  alluvions,  but  results  from  a  long  course  of 
cultivation,  when  large  quantities  of  animal  and  vegetable 
matters  are  employed.  The  2)eaty  soils  are  also  sufiiciently 
definite  to  form  a  distinct  class.  A  short  description  of  these 
soils,  including  the  characters  by  which  they  may  be  recog- 


CHEMICAL  CLASSIFICATION  OF  SOILS.  243 

nized,  their  general  mode  of  improvement,  and  their  natural 
adaptation  to  the  various  crops  cultivated  by  the  farmer,  may 
not  be  inappropriate. 

1.  Siliceous  soils.  In  the  silicious  soils,  from  whatever 
class  of  rocks  they  are  derived,  silex  or  silica  is  the  predomi- 
nant earth.  These  soils  originate  generally  either  from  the 
disintegration  of  silicious  rocks,  from  glacial  action,  or  from 
streams  and  rivers  which  pass  over  sandstone  rocks. 

Properties.  Siliceous  soils  are  either  gravelly  or  sandy, 
or  a  mixture  of  both  ;  they  are  always  of  a  loose  texture,  per- 
mitting the  water  to  pass  easily  through  them. 

They  absorb  but  little  moisture  from  the  atmosphere,  and 
part  with  it  readily,  on  the  application  of  heat.  Hence  in 
seasons  of  drought,  they  become  mealy,  and  their  vegetation 
is  scorched  and  dried  up.  As  sandy  and  gravelly  soils  do 
not  generally  combine  with  manure  or  vegetable  matter, 
which  is  introduced  into  them,  they  easily  part  with  it,  and 
hence  they  have  been  denominated  hungry  soils.  If  the  sub- 
soil is  gravelly  or  sandy,  they  are  subject  to  leaching,  and  the 
vegetable  matter  passes  through  them  almost  as  fast  as  it  is 
rendered  soluble  in  water. 

Sandy  and  gravelly  soils  are  generally  warm  and  quick, 
and  from  their  want  of  adhesiveness,  easily  tilled.  They  dif- 
fer from  absolute  barrenness  to  a  high  degree  of  fertility. 
When  wholly  without  cohesion  in  their  parts,  they  are  entirely 
barren,  and  can  only  be  made  fertile  by  the  admixture  of 
other  substances.  This  is  the  case  often  with  the  coarser 
gravels.  When  fine  or  sandy,  and  mixed  with  aluminous 
earth,  or  magnesia  and  a  suitable  proportion  of  organic  mat- 
ter, they  become  very  fertile,  especially  if  they  have  a  tena- 
cious sub-soil. 

Mode  of  improvement.  A  sandy  or  gravelly  soil  may  be 
improved  by  mixing  clay  or  peat  compost  with  them,  so  as  to 
increase  their  adhesiveness,  their  power  of  absorbing  water  and 


244  GEOLOGY  AND  CHEMISTRY  OF  SOILS. 

of  retaining  manure.  The  stones  should  not  be  all  removed, 
as''they  aid  in  retaining  heat  and  moisture. 

These  soils  are  naturally  better  fitted  for  rye,  barley  and 
Indian  corn  than  for  wheat;  but  from  their  porous  charac- 
ter, they  are  particularly  fitted  for  those  crops  which  are  cul- 
tivated for  the  tubers  of  their  roots,  such  as  potatoes,  turnips, 
beets,  etc.  For  the  tuberous  roots,  however,  they  must  pos- 
sess somewhat  the  characteristics  of  loam.  They  are  also 
well  adapted  to  timothy,  clover  and  red-top. 

2.  Aluminous  or  clai/  soils  are  those  in  which  clay  in  some 
of  its  varieties  predominates.  They  vary  in  composition. 
Silica  constitutes  more  than  one  half  of  their  substance. 
These  soils  originate  generally  from  the  tertiary  beds  of  clay, 
but  are  often  formed  by  the  disintegration  of  argillaceous 
rock,  and  by  the  agency  of  rivers,  especially  near  their 
ttiouths,  where  the  tides  and  waves  throw  back  aluminous 
matter,  which  is  either  contained  in  the  water  in  a  finely  di- 
vided state,  or  worn  ofi"  from  the  cliffs  of  clay  near  the  shores. 

Aluminous  soils  are  stiff  and  heavy,  generally  destitute 
of  stones  and  very  tenacious  of  water  ;  of  which  they  absorb 
large  quantities,  and  yield  it  up  with  difficulty.  When  wet, 
they  have  the  appearance  of  mortar,  and  adhere  to  the  plough, 
when  it  passes  through  them.  When  dry,  they  break  up  in- 
to lumps  when  ploughed,  or  contract  upon  the  surface,  leav- 
ing small  fissures  crossing  each  other  in  various  directions ; 
hence,  they  are  subject  to  the  extremes  of  wet  and  drought. 
The  clay  soils  differ  in  texture  according  to  the  quantity  of 
other  earths.  A  large  quantity  of  silirrous  earth  renders  them 
less  cohesive ;  and  if  vegetable  and  animal  substances  are 
added,  they  often  become  similar  to  loams.  They  are  natu- 
rally cold,  especially  when  they  are  light  colored,  in  which 
case  they  are  not  easily  heated  by  the  sun's  rays.  They 
are  capable  of  uniting  chemically  with  vegetable  acids 
and  earths,  a  circumstance  of  great  practical  importance,  as 
it  renders  them  very  retentive  of  manures,  so  that  in  this  re- 


CHEMICAL  CLASSIFICATION  OF  SOILS.  245 

spect,  they  are  the  opposite  of  sandy  and  gravelly  soils.  Clay 
soils  are  of  every  quality,  from  a  dead,  barren  mass,  to  the 
rich  clay  loams,  which  are  some  of  the  most  fertile  and  pro- 
fitable soils  which  are  cultivated.  Hence  their  fertility  will 
depend  upon  the  proportion  of  other  earths,  the  quantity  of 
animal  and  vegetable  matter  they  contain,  and  the  character 
of  the  sub-soils.  Common  clay  is  wholly  barren.  Mixed  with 
calcareous  or  siliceous  earth,  it  is  nearly  so;  but  when,  in 
addition,  it  contains  large  quantities  of  manure,  it  becomes 
comparatively  fertile,  if  the  sub-soil  is  sand,  or  such  as  to 
permit  the  water  to  drain  oft';  but  if  the  sub-soil  is  impervi- 
ous to  water,  they  are  always  cold,  wet,  and  unfriendly  to 
those  crops  which  require  the  heat  of  summer  to  bring  them 
to  maturity. 

The  most  fertile  of  these  soils  are  the  alluvial  clay  soils. 
These  are  formed  at  the  mouths  of  rivers,  where  the  sea  exerts 
its  influence  upon  the  fine  materials  brought  down  by  their 
waters,  as  they  flow  over  argillaceous  rocks.  They  often  be- 
come mixed  with  animal  and  vegetable  substances,  and  ap- 
proach rich  clay  loams,  of  the  most  fertile  and  valuable  qual- 
ity. The  common  clay  bottoms  may  be  converted  into  fertile 
clay  loams,  by  cultivation. 

Mode  of  improvement.  Aluminous  soils  are  improved  by 
admixture  of  siliceous  and  calcareous  sand  and  peat  muck. 
This  renders  them  more  friable  and  more  easily  tilled. 

Sand  often  forms  the  sub-soil,  in  which  case  sub-soil 
ploughing  may  be  resorted  to,  by  which  the  sand  and  clay 
will  become  incorporated.  This  is  diflferent  from  trench 
ploughing,  in  which  two  ploughs  are  used,  the  one  to  turn  the 
upper  soil,  and  the  other  to  bring  up  the  sub-soil  to  the  sur- 
face. But  in  sub-soil  ploughing  no  portion  of  the  sub-soil  is 
brought  to  the  surface,  but  merely  loosened  and  pulverized. 
By  this  process,  the  air  and  water  exert  a  fertilizing  influence 
upon  it,  and  then  it  is  incorporated  with  the  clay  by  trench 
21 


246  GEOLOGY  AND  CHEMISTRY  OF  SOILS. 

ploughing.  If  the  sub-soil  is  similar  to  the  soil  in  composi- 
tion, the  same  process  may  be  gone  through,  but  in  addition, 
the  ground  should  be  drained,  to  let  the  water  pass  off. 

Crops.  Clay  soils  are  best  adapted  to  wheat,  timothy  and 
oats ;  and  where  the  bottom  is  dry,  to  potatoes  and  clover. 
Clay  loams,  containing  carbonate  of  lime,  are  the  best  wheat 
soils  known.  This  arises  from  the  fact  that  they  give  stabil- 
ity to  the  roots,  furnish  the  requisite  alkalies,  and  absorb 
gaseous  bodies,  which  are  essential  to  that  crop.  They  are 
not  fit  for  the  tap-roots,  although  such  crops  exert  a  favorable 
influence  upon  them  by  dividing  the  soil.  They  should  be 
ploughed  in  the  fall,  to  be  broken  down  and  pulverized  by 
the  frosts  during  the  winter,  especially  if  intended  for  an 
early  summer  crop. 

3.  Calcareous  soils  contain  large  quantitiesof  carbonate  of 
lime,  under  the  varieties  of  chalk,  marble,  calcareous  marl, 
siliceous,  ferruginous  and  magnesian  limestones.  It  is  not 
necessary  for  a  soil  to  be  composed  principally  of  this  earth, 
in  order  to  render  it  calcareous,  a  smaller  portion  of  it  being 
required  to  give  the  name,  than  of  the  other  soils  above  men- 
tioned. Calcareous  soils  originate  from  the  disintegration  of 
limestone  rocks,  which  are  most  abundant  in  the  secondary 
formation  ;  especially  from  the  chalk  or  cretaceous  group. 
These  soils  are  often  washed  some  distance,  and  cover  over 
large  areas.  Some  of  them  contain  fossils  and  some  (as  those 
from  the  primitive  limestone)  do  not. 

Properties.  Calcareous  soils  are  either  gravelly  or  sandy, 
depending  upon  the  degree  of  comminution.  They  are  more 
adhesive  and  absorb  more  water  than  siliceous,  and  less  than 
aluminous  soils.  But  the  most  striking  property  is  their 
power  of  causing  the  decay  of  vegetable  matters,  and  of  re- 
taining several  gaseous  products  for  the  wants  of  vegetation. 
Calcareous  soil  is  friable  and  easily  tilled  ;  not  suflering  either 
from  drought  or  too  great  moisture,  provided  the  sub-soil  is 
not  too  retentive  of  water. 


CHEMICAL  CLASSIFICATION  OF  SOILS.  247 

Tests.  Take  a  small  quantity  of  the  soil ;  heat  it  to  300° 
F.  and  then  place  it  in  a  glass  and  cover  it  with  pure  water ; 
drop  on  a  few  drops  of  hydrochloric  acid  ;  if  bubbles  of  gas 
come  up  through  the  water  it  contains  carbonate  of  lime. 
The  pebbles  will  also  show  of  what  the  soil  is  principally  com- 
posed. The  chalky  variety  is  white,  and  reflects  the  heat 
more  than  the  darker  varieties. 

Degree  of  fertility.  Calcareous  soils  when  combined  with 
clay,  with  other  earths  and  vegetable  matters,  are  among  the 
most  fertile  soils.  If  combined  with  siliceous  sand  and  grav- 
el, they  are  light,  loose  and  often  unfertile ;  but  when  com- 
bined with  aluminous  earth,  they  are  the  richest  soils  in  all 
wheat-growing  countries. 

Mode  of  improvement.  As  pure  calcareous  sand  or  gravel 
is  too  friable  and  loose  for  the  support  of  vegetation,  it  may 
be  improved  by  adding  clay-loam,  or  even  pure  clay ;  and 
sometimes  sand  and  peat-muck,  are  highly  valuable.  Lime 
tends  to  exhaust  the  humus  of  the  soil;  large  quantities  of 
yard-dung  or  vegetable  matter  should  therefore  be  supplied 
to  keep  up  the  fertility. 

Crops.  Tillage  crops  are  best  adapted  to  calcareous  soils, 
such  as  peas,  turnips,  barley,  clover,  wheat  and  Indian  corn. 
They  give  a  peculiar  sweetness  to  the  grass  which  grows 
upon  them,  or  rather  favor  the  sweet  grasses,  and  hence  are 
excellent  soils  for  pasture  lands. 

4.  The  magnesian  soils  which  result  from  serpentine  rocks, 
and  magnesian  limestones  are  very  fertile  soils,  but  not  of 
sufficient  extent  to  be  farther  noticed  in  this  place. 

5.  Peaty  soils  are  composed  of  large  quantities  of  vegeta- 
ble matter  mixed  with  earthy  ingredients,  lime,  silica,  alu- 
mina and  oxide  of  iron.  They  abound  in  the  eastern  part  of 
Massachusetts,  and  in  most  temperate  regions  of  the  earth. 

Origin.  These  soils  originate  from  growing  vegetables, 
such  as  mosses  in  swamps  where  there  is  so  much  water  that 
the  roots,  leaves  and  branches  of  trees   accumulate,  and  are 


248  GEOLOGY  AND  CHEMISTRY  OF  SOILS. 

prevented  from  decomposition.  In  some  cases  a  bed  of  sev- 
eral feet  in  thickness  is  almost  pure  vegetable  matter,  and 
becomes  hardened  into  peat  fit  for  fuel ;  in  others,  the  tex- 
ture is  loose  and  spongy. 

Properties.  The  properties  of  peat  soils  vary  according 
to  the  character  of  the  surrounding  soils ;  where  the  earthy 
materials  are  clay  they  make  a  compact  soil,  retentive  of  wa- 
ter, and  capable  of  being  made  very  productive ;  when  the 
earth  is  silica,  they  are  more  light  and  spongy,  and  permit  the 
water  to  pass  off.  When  mixed  with  calcareous  matter  they 
are  reduced  to  a  fine  black  mould  ;  if  the  surrounding  rocks 
contain  pyrites  they  often  become  acid  ;  if  near  the  ocean, 
they  become  mixed  with  sea-salt.  They  sometimes  contain 
bitumen.  The  properties  therefore  depend  upon  their  tex- 
ture, the  earths  with  which  they  are  combined,  and  the  salts 
which  they  contain.  Analysis  is  the  only  sure  means  of 
showing  their  exact  composition. 

Mode  of  improvement.  Peat  swamps  must  first  be  drained, 
to  carry  off  the  water,  which  renders  them  soft  and  spongy  ; 
they  will  then  become  hard.  Siliceous  and  aluminous  earth 
may  then  be  spread  upon  them ;  yard-manure  and  lime  or 
ashes  will  also  improve  their  properties  by  decomposing  the 
vegetable  matters.  Some  recommend  paring  the  surface 
and  burning  it ;  then  by  scattering  the  ashes  over  the  soil,  all 
the  acid  properties  will  be  neutralized.  The  peat  itself  makes 
an  excellent  compost  manure  for  the  uplands,  and  should  be 
carried  into  the  barn-yard  and  mixed  with  yard  and  stable 
manures. 

Degree  of  Jertility.  Peat  soils  are,  or  can  be  made  very 
fertile  ;  the  want  of  fertility  is  not  owing  to  any  deficiency  of 
vegetable  matter,  but  to  their  texture  and  to  the  want  of 
this  matter  in  a  soluble  state,  so  as  to  nourish  plants.  When 
this  is  converted  into  vegetable  food  and  the  texture  im- 
proved by  draining  and  mixture  of  other  earths,  they  are 
the  most  profitable   of  all    soils ;  especially  is  this  the  case 


CHEMICAL  CLASSIFICATION  OF  SOILS.  249 

in  New  England,  where  these  lands  are  in  too  many  cases 
suffered  to  lie  waste.  Our  peat  swamps  are  decidedly  the 
most  valuable  of  all  our  soils,  because  they  contain  food  for 
the  plants  of  a  thousand  generations ;  they  ought  rather 
to  be  called  manures  than  soils. 

Crops.  "  Peat  soils,"  says  Buel,  "are  best  calculated  for  oats, 
potatoes,  rye,  turnips,  carrots  and  Indian  corn ;  clover,  timo- 
thy, red-top  and  other  grasses."  If  the  swamps  in  the  east- 
ern part  of  Massachusetts  were  fitted  for  grass,  they  would 
become  more  profitable  than  any  other  lands  which  are  culti- 
vated. 

6.  Alluvial  soils.  These  have  already  been  described, 
p.  231.  It  is  a  remarkable  fact,  that  according  to  the  analy- 
sis of  Prof  Hitchcock,  the  alluvial  soils  of  New  England,  and 
of  the  West,  contain  less  vegetable  matter  than  most  other 
soils.  Their  fertility,  therefore,  must  depend  upon  the  min- 
eral ingredients  being  in  a  more  finely  divided  state,  and  to 
their  power  of  converting  insoluble  into  soluble  food ;  it  is 
hence  inferred,  that  these  soils  will  be  soonest  exhausted,  un- 
less supplied  with  vegetable  and  animal  matters. 

7.  Loamy  soils.  Loams  occupy  an  intermediate  place  be- 
tween clayey  and  sandy  soils,  and  originate  from  a  constant 
course  of  tillage,  and  the  application  of  animal  and  vegetable 
manures,  for  a  course  of  years.  It  is  the  desire  of  our  far- 
mers, to  bring  all  their  soil  into  the  state  of  loams. 

Properties.  The  properties  of  loams  are  well  known ; 
they  are  less  tenacious  than  clay,  and  more  so  than  sand, 
They  are  very  friable,  capable  of  sustaining  drought  or  wetness 
and  easily  ploughed  at  almost  every  season  of  the  year.  They 
are  the  most  desirable  of  all  soils.  The  alluvial  soils  describ- 
ed in  the  last  section  answer  to  the  loams,  as  the  materials 
are  fine  and  beautifully  mingled  together.  They  are  divided 
by  Sinclair  into  four  sorts  :  I.  sandy  ;  2.  gravelly ;  3.  clay- 
ey ;  and  4.  peaty. 

21* 


250  IMPROVEMENT  OF  THE  SOIL 


CHAPTER  VI. 

IMPROVEMENT  OF  THE  SOIL.    . 

The  improvement  of  the  soil  is  the  great  object  of  agricul- 
tural chemistry.  From  a  knowledge  of  the  rocks  and  the 
agencies  which  have  been  active  in  crumbling  them  into  soil ; 
from  the  physical  and  chemical  character  of  soils,  and,  final- 
ly, from  the  analysis  in  this  country,  we  learn  what  they  gene- 
rally need  to  insure  fertility.  By  an  extensive  analysis  it  ap- 
pears that  the  earths  exist  in  our  soils  in  sufficient  quantities, 
with  the  exception  perhaps  of  lime  ;  that  the  vegetable  mat- 
ters, alkalies  and  salts,  are  consumed  by  a  continual  course 
of  cropping,  and  must  be  constantly  supplied.  The  mode  of 
improvement,  then,  relates  principally  to  the  application  of 
vegetable  and  animal  matters,  alkalies  and  saline  compounds, 
which  latter  includes  carbonate  of  lime. 

The  agents  which  we  have  considered  in  the  first  two 
chapters,  such  as  heat,  light,  affinity  and  electricity,  depend 
chiefly  for  their  efficacy  upon  the  character  of  the  soil.  Vege- 
table substances,  for  example,  render  a  sandy  soil  more  re- 
tentive of  water,  and  of  caloric,  as  well  as  more  compact. 
They  render  a  clayey  soil  less  retentive  of  water,  but  warmer 
and  more  friable  and  permeable  by  the  roots  of  plants. 

Carbonate  of  lime  has  been  found  an  earthy  ingredient  of 
nearly  all  rich  soils  ;  and  as  our  soils  are  nearly  destitute  of 
it,  they  would  generally  be  benefitted  by  its  addition.     Alka- 
lies and  saline  compounds,  such  as  potash,  soda,  ammonia, 
nitre,  common  salt,  etc.  are,  as  we  have  seen,  necessary  for 
the  maturity  of  plants  ;   and,  as  they  are  exhausted  by  tillage, 
they  must  be  supplied,  to  keep  up  the  fertility.     There  are 
other  modes  of  improvement,  which  pertain  to  the  processes  ~ 
of  tillage,  which  are  all  important,  and  which  constitute  the 
principal  features  of  the  modern  system  of  husbandry.     We 


BY  ADDITION  OF  EARTHS.  251 

have  already  referred,  p.  242,  on  the  classification  and  de- 
scription of  soils,  to  several  modes  of  amelioration.  In  this 
chapter  we  design  to  describe  at  length,  these  and  other  modes 
of  improvement,  and  to  explain  the  chemical  and  mechani- 
cal principles  upon  which  the  various  methods  are  based. 

The  following  topics  may  fairly  include  all  that  is  impor- 
tant on  this  branch  of  the  subject. 

1.  Improvement  of  the  soil  by  adding  earths  not  existing 
in  it,  or  existing  in  too  small  quantities. 

1.  Improvement  of  the  soil  by  draining  and  irrigation. 

2.  By  fallow  crops  and  turning  in  green  crops. 

3.  By  rotation  or  interchange  of  crops. 

4.  By  root  culture. 

5.  By  manures. 

6.  By  tillage. 

As  the  subject  of  manures  is  one  of  very  great  importance 
to  the  farmer,  and,  as  it  is  somewhat  distinct  from  the  other 
modes  of  improvement,  it  will,  in  connection  with  that  of  til- 
lage, occupy  a  separate  chapter. 

In  the  discussion  of  the  above  topics,  it  will  be  necessary 
to  repeat  many  principles  already  suggested.  As  an  apology 
for  this,  we  simply  urge  the  great  importance  to  the  farmer  of 
thoroughly  understanding  the  application  of  these  principles 
in  all  their  connections  and  relations. 

Sect.  1 .  Improvement  of  the  Soil  hy  the  Addition  of  Earths 
not  existing  in  it,  or  existing  in  too  small  quantities. 

This  mode  of  improvement  was  described  generally  in  the 
chemical  classification  of  soils.  A  few  remarks  only  need  be 
added  here,  particularly  applicable  to  the  soils  of  New  Eng- 
land, and,  with  a  few  exceptions,  to  this  country. 

1.  Carbonate  of  lime.*      It  is  hardly  necessary  to  repeat 

*  There  is  no  subject,  respecting  which  there  is  a  greater  diversity 
of  opinion,  among  practical  farmers,  than  that  of  the  application  of 
lime.     It  is  said  by  some,  to  burn  up  the  vegetable  matter ;  while  it  is 


252  IMPROVEMENT  OF  THE  SOIL 

here,  that  most  of  our  soils  are  nearly  destitute  of  lime,  al- 
though reposing  on  limestone  rocks.  We  have  no  soils  which 
are  strictly  calcareous,  and  hence  this  earth  may  be  added 
without  the  least  fear  of  injury,  but  with  the  certainty  of  ulti- 
mate and  permanent  benefit.  The  quantity  need  not  be 
large ;  four  or  five  per  cent,  and  even  less  will  essentially  im- 
prove the  texture  of  the  soil,  and  supply  the  necessary  earthy 
ingredients,  and  it  is  in  these  two  respects  that  we  are  now 
speaking  of  it.  Hence  it  should  be  applied,  for  these  objects, 
in  the  form  of  marl,  shell  or  ground  limestone.  Quick  or 
slacked  lime  applied  to  the  soil  soon  becomes  converted,  in 
part,  into  carbonate,  and  air-slacked  lime  is  already  partially 
carbonated  ;  but  the  application  of  lime  in  this  form  is  better 
suited  to  it  as  a  saline  manure.  The  effect  of  lime,  as  an 
earthy  ingredient,  is  to  render  cold,  stiff  clay  soils  more  fria- 
ble and  light ;  of  course  dryer  and  more  easily  heated  by  the 
rays  of  the  sun.  Upon  sandy  soils,  the  effect  is  just  the  re- 
verse ;  and,  in  addition,  it  enables  such  soils  to  retain  the 
manures  placed  upon  them,  and  counteracts  the  electro-nega- 
tive character  which  the  silicic  acid  or  silex  imparts  to  them. 
2.  Sand  ox  gravel.  When  a  soil  is  too  clayey  or  peaty,  its 
texture  may  be  improved  by  the  addition  of  sand  or  gravel. 
Their  effect  upon  such  soils  is  similar  to  that  of  lime.  The 
sand  gives  to  the  clay  a  better  consistency,  and  renders  the 
peat  more  compact.  It  is  easy  to  understand  how  this  is ; 
but  it  has  been  a  question  of  some  difficulty  to  determine 
whether  sand  or  coarse  gravel  is  the  better  form  in  which  to 
apply  siliceous  matter.  This  question  is  one  of  easy  solu- 
tion, provided  all  the  circumstances  are  understood.  If  the 
soil  is  peaty,  the  fine  gravel  will  produce  a  more  immediate 
effect,  and  loam  is  better  than  gravel ;  but  coarse  gravel  will 
be  more  durable,  because  it  not  only  supplies  the  earthy  in- 
believed,  by  others,  to  add  greatly  to  the  fertility.  When  applied  as 
a  carbonate,  no  ill  effects  can  be  experienced.  In  its  caustic  state,  it 
may  prove  injurious  by  forming  with  the  vegetable  matter  an  insoluble 
substance,  which  thus  removes  a  part  of  the  vegetable  food. 


1 


BY  SAND  AND  CLAY.  253 

gredients  which  influence  the  texture,  but  also  the  decom- 
posable minerals,  which  are  equally  necessary  for  the  growth 
of  vegetables.  Loam,  or  fine  gravel,  spread  directly  upon 
peat  meadows,  after  they  are  drained,  will  render  them  fertile 
at  once ;  provided  that  a  small  quantity  of  lime,  ashes,  or 
other  alkaline  substance  is  added,  to  correct  the  acidity,  and 
dissolve  the  vegetable  matter. 

If  the  soil  is  clayey,  coarse  gravel  will  ultimately  prove  the 
most  valuable,  for  the  same  reason  as  above,  and  loam  or  fine 
sand  will  produce  a  more  immediate  effect ;  hence,  the  de- 
cision of  this  question,  and  the  practice,  w^ill  be  one  way  or 
the  other,  according  to  the  object  we  have  in  view  in  making 
the  improvement.  If  a  sufficient  quantity/  of  loam  could  be 
added,  it  would  undoubtedly  be  better  than  either  sand  or 
gravel. 

3.  Clay.  Sandy,  light,  peaty  and  calcareous  soils  are 
often  benefitted  by  the  addition  of  clay.  The  mode  of  ap- 
plying it  (as  derived  from  experience  and  confirmed  by  theo- 
ry), is  to  spread  it  upon  the  soil  in  the  fall  or  commencement 
of  winter,  that  the  frost  may  break  it  down,  and  render  it  fit 
to  be  intimately  mingled  with  the  soil,  by  the  process  of 
ploughing  and  harrowing  in  the  spring.  Chaptal  recommends 
the  practice  of  baking  and  then  pulverizing,  by  which  pro- 
cess it  approaches  nearer  to  sand  in  its  physical  properties. 

The  utility  of  clay  in  agriculture  has  long  been  acknow- 
ledged, but  the  manner  in  which  it  operates  is  yet  a  little 
doubtful.  Some  things,  however,  are  well  settled.  It  adds 
its  adhesive  and  retentive  properties  to  sandy  and  peaty  soils, 
and  furnishes  one  indispensable  earthy  ingredient ;  but  its 
effects  are  not  wholly  accounted  for  by  the  texture  which  it 
imparts.  We  must  resort  to  its  composition.  Now  it  has 
been  found  that  some  of  our  clays,  especially  the  clay  marls, 
contain  small  quantities  of  carbonate  of  lime.  By  adding 
one  earth,  therefore,  we  actually  add  two,  both  of  which  are 
especially  important  to  soils  of  the  above  description ;  for, 


254 


IMPROVEMENT  OF  THE  SOIL 


Oxide  of  Manganese  0.56 

Lime  0.56 

Magnesia  .44 

Sulphur  and  loss  3.22 


where  there  is  too  much  sand  or  silica,  both  clay  and  carbo- 
nate of  lime  operate  to  equalize  the  electrical  forces ;  both 
act  as  converters  of  vegetable  fibre  into  vegetable  food. 

A  specimen  of  common  blue  clay  from  Lowell,  analyzed  by 
Prof.  Hitchcock,  gave 

Water  and  organic  matter        4.0 

Silica  61.52 

Alumina  20.50 

Protoxide  of  iron  9.82 

It  will  be  seen  by  this  analysis,  that  there  is  a  large  quan- 
tity of  protoxide  of  iron,  and  this  explains  further  its  influ- 
ence. "  Our  common  clays,"  says  Dr.  Dana,  "  contain  more 
or  less  of  sulphuret  of  iron.  The  conversion  of  this  into  the 
persulphate  of  iron,  is  the  natural  consequence  of  exposure  ; 
free  sulphuric  acid  then  results,  which  acts  on  any  lime  in 
the  soil  forming  sulphate  of  lime,  or  gypsum."  But  the  most 
important  effect  of  the  protoxide  is  that  in  passing  into  the 
peroxide,  it  tends  to  induce  decay  in  the  vegetable  matters, 
which  are  in  contact  with  it ;  hence  clay  acts  upon  a  soil 
as  an  alkali,  an  alkaline  earth,  and  a  metallic  oxide. 

Finally,  clay  has  the  property  of  absorbing  gaseous  bodies, 
which  are  useful  in  vegetation.  Liebigr  attributes  to  it  the 
power  of  absorbing  ammonia,  from  which  plants  derive  their 
nitrogen.  Daubeny  regards  this  power  in  a  soil,  as  an  in- 
dispensable condition  of  fertility. 

As  sand  will  improve  a  clayey  or  peaty  soil,  and  clay  a 
sandy  soil,  it  is  matter  of  no  little  astonishment  that  New 
England  farmers  have  not  resorted  more  frequently  to  this 
mode  of  amelioration.  In  various  parts  of  the  country,  sand 
hills,  peat  swamps  and  clay  beds,  are  so  situated  often,  that 
it  would  be  the  easiest  thing  in  the  word  to  transfer  portions 
of  the  one  to  the  other,  to  the  mutual  improvement  of  all. 
It  sometimes  happens,  that  a  soil  is  reduced  to  an  inipalpa- 
ple  powder  when  dry,  and  to  a  soft  paste  when  wet, -while  the 
earthy  and  vegetable  ingredients  are  in  the  right  proportions 
to  ensure  fertility.     Such  a  state  of  the  soil  results  from  a 


BY  DRAINING.  ^o5 

long  course  of  tillage,  and  is  due  to  the  fact  that  the  miner- 
als are  all  decomposed  by  the  action  of  growing  plants,  and, 
without  decomposable  minerals  in  the  soil,  no  plants  grown 
upon  it  will  come  to  maturity.  Such  lands,  therefore,  re- 
quire gravel,  sand  or  loam,  and  as  in  the  cases  above  mention- 
ed, the  latter  has  been  found  to  produce  the  best  effect,  while 
theory  at  least  would  lead  to  the  opinion  that  the  former 
would  be  most  durable. 

The  general  theory  relative  to  these  modes  of  improve- 
ment is,  first  to  improve  the  texture  and  consistency  and 
equalize  the  electrical  state  of  the  soil,  and  secondly  to  fur- 
nish those  decomposable  minerals  which  plants  must  have 
in  order  to  mature  their  seeds. 

There  is  a  limit,  however,  to  these  methods,  while  time 
and  expense  are  required  to  carry  out  a  system  sufficiently 
rigorous  to  produce  the  highest  effect;  but  if  the  farmer  will 
have  patience,  coupled  with  perseverance,  he  may  have  the 
satisfaction  of  seeing  his  soils  gradually  but  surely  approach- 
ing to  the  best  possible  texture,  and  to  the  most  favorable  pro- 
portions of  all  the  mineral  ingredients. 

Sect.  2.  Improvement  of  the  Soil  hy  Draining  and  Irri- 
gation. 
Wet  soils  originate  from  two  causes.  1.  When  the  water, 
which  falls  upon  the  surface,  is  retained  by  a  retentive  sub- 
soil, as  is  often  the  case  with  level  lands  on  clay  bottoms.  2. 
When  the  water,  which  passes  beneath  the  surface  along  the 
water-hearing  strata,  meets  with  dikes,  or  strata,  which  have 
been  broken  off,  and  incline  in  different  directions.  In  the 
latter  case,  if  the  land  is  much  inclined,  there  will  be  springs 
formed  at  the  out-cropping  of  these  strata,  and,  if  the  surface 
is  level,  the  pressure  of  the  water,  from  the  surrounding  high 
lands,  will  force  it  up  to  the  surface,  and  produce  a  swamp, 
or  too  great  a  degree  of  moisture.  In  both  cases  the  soil  is 
rendered  cold  and  unfruitful,  hence  fertility  can  be  restored 
only  by  removing  the  cause  of  barrenness. 


256  IMPROVEMENT  OF  THE  SOIL 

I.  Draining.  This  mode  of  amendment  can  be  applied 
only  to  stiff  clays  and  swamps,  or  to  lands  which  have  a  hard 
and  retentive  sub-soil,  so  that  the  water,  in  the  ordinary 
course  of  things,  will  not  pass  off,  and  leave  the  land  com- 
paratively dry,  for  a  considerable  portion  of  the  season. 

The  operations  of  draining  are  therefore  confined  to  sur- 
face draining,  draining  the  soil,  and  draining  the  sub-soil. 

1.  Draining  the  surface.  In  stiff  clay  soils,  if  the  land  is 
level  or  moderately  inclined,  the  water  from  rains  and  snows 
is  liable  to  remain  on  the  surface,  forming  pools  in  every  lit- 
tle hollow.  This  prevents  the  seeds,  if  sown,  from  sprout- 
ing, and  injures  the  crop.  When  this  water  is  evaporated, 
the'  surface  becomes  hard  and  impenetrable  by  air  and  heat, 

and  by  the  roots  of  vegetables. 

Fig.  14. 
This  evil  is  some-  au 

timeseffectuallyre-  mMT'^^^^^^mZ^^^^ 
medied  by  simply 

throwing  the  land  into  ridges  (Fig.  U)  by  a  process  called 
back  furrowing,  a  process  which  every  farmer  knows  well 
how  to  perform.  It  will  be  seen  by  inspection  of  this  figure, 
that  the  water  as  it  falls  upon  the  crown  of  the  ridge  h  h  will 
pass  off  down  both  sides  in  the  same  way  that  it  does  when 
it  falls  upon  the  roof  of  a  house,  and  either  settle  into  the 
sub-soil,  if  porous,  or  into  the  furrows  a  c  between  the  ridges. 

If  the  soil  has  an  uneven  surface  and  the  water  accumu- 
lates in  the  hollows,  an  open  drain  is  the  only  effectual  re- 
medy. 

But  in  cases  where  the  surface  is  level  and  the  sub-soil 
hard  and  retentive,  resort  must  be  had, 

2.  To  draining  the  soil  This  is  effected  by  penetrating  the 
sub-soil  so  as  to  form  a  passage  for  the  water  to  pass  off  from 
the  field,  or  a  reservoir  into  which  it  may  ooze  from  the  sod. 

The  drains  by  which  this  is  effected  may  be  either  open 
or   covered.      The  latter,  or  underground   drains,  are    the 


BY  DRAINING. CONSTRUCTION  OF  DRAINS. 


257 


cheapest,  most  durable  and  most  effectual ;  for,  aside  from  their 
convenience,  a  considerable  quantity  of  land  is  saved  for  cul- 
tivation. 

(Fig.  15.) 


Before  constructing  a  drain  for  this  purpose,  it  is  neces- 
sary to  examine  the  land,  and  ascertain  where  the  springs 
are.  Most  cases  of  surface-draining  refer  to  swamps,  or 
low  lands.  Suppose  BOD  (Fig.  15)  is  a  swamp,  or  low 
ground  in  which  the  water  collects,  either  from  the  high 
lands,  or  from  springs  in  the  margin  B  D,  or  anywhere  in 
the  centre  of  the  meadow.  The  first  thing  to  be  done,  in 
this  case,  is  to  make  an  outlet  for  conducting  the  water  away 
to  some  stream  as  at  O  S.  The  second  is  to  run  a  drain 
through  the  centre  from  Cto  O,  and  all  around  the  margin 
B  D,  to  cut  off  the  springs,  and  to  conduct  the  water  into  the 
main  drain  A,  or  outlet.  In  each  case  these  drains  should 
be  sunk  into  the  sub-soil,  and  if  much  water  flow  in  them 
they  should  be  open,  especially  the  central  drain.  In  this 
way  the  swamp  can  be  rendered  perfectly  dry  and  capable  of 
being  cultivated. 

Construction    of  under-ground    drains.      Under-ground 
drains  should  be  from  two  to  three  feet  in  depth,  in  order 
22 


258  LMPROVEMENT  OF  THE  SOIL 

that  they  may  not  be  injured  by  the  tread  of  cattle,  and  the 
heavy  loads,  which  may  pass  over  them.  The  sides  should 
be  a  little  flaring,  that  is,  the  drain  should  be  a  few  inches 
wider  at  the  top  than  at  the  bottom. 

Fig.  16. 

The  materials  used  for  filling  up  the  lower 
portion  of  the  drain,  may  be  small  stones,  tiles 
or  any  hard  substances.  1.  If  no  water  of  con- 
sequence is  to  flow  in  them,  they  may  be  filled 
up,  with  these  small  stones,  to  the  depth  of 
from  ten  to  fifteen  inches,  and  the  remainder 
filled  up  with  gravel  and  loam.  2.  But  in 
case  water  is  expected  to  flow  in  them,  a  con- 
duit must  be  laid  on  the  bottom  (Fig.  16.) 
This  is  made  by  building  a  wall,  on  each  side 
with  stone  or  brick,  about  six  or  eight  inches 
in  height  and  six  in  width,  and  covering  it  over 
with  flat  stones  so  tight  that  mice  or  moles 
through  it,  and  let  in  the  soil  from  above  and  choak  it  up. 
If  the  earth  is  soft,  the  bottom  also  should  be  lined  with 
stones.  Upon  the  top  of  the  flat  stones,  and  upon  the  sides, 
fill  in  small  stones  c  to  the  height  of  several  inches  according 
to  the  depth  of  the  drain,  and  then  cover  the  whole  with 
earth  a  b,  rounding  the  surface,  so  that  when  the  whole  set- 
tles, it  may  be  even  with  the  ground. 

The  conduit,  in  case  stones  cannot  be  found,  may  be 
made  of  tiles  from  clay,  resembling  earthen  ware.  These 
are  laid  together  and  form  a  complete  tube  for  conducting 
away  the  water. 

In  some  cases  the  surface  may  be  drained  by  digging  deep 
pits  and  filling  them  with  stone.  This  mode  is  adopted  when 
the  sub-soil  is  hard  or  clayey,  and  a  few  inches  below,  are  stra- 
ta of  sand  or  gravel.  By  digging  through  the  retentive  sub- 
soil, the  surface-water  will  run  off". 

3.  Draining  the  sub-suil.    This  process  becomes  necessary 


BY  DRAINING  THE  SUB-SOIL. 


259 


in  consequence  of  the  inclination  of  the  strata  or  layers  of 
clay  and  rock  near  the  surface.  The  sub-soil  is  often  thus 
constituted,  and  these  incline  to  the  surface,  or  crop  out  upon 
the  sides  of  hills.  The  water-bearing  strata  which  lies  below 
the  sub-soil  being  brought  to  the  surface,  produce  springs 
which  are  a  fruitful  source  of  wet  soils. 

The  water  in  some  cases  rises  up  through  the  sub-soil  by 
the  force  of  pressure  from  the  neighboring  highlands,  and 
produces  a  swamp. 

In  case  of  sub-soil  draining,  the  object  is  to  intercept  the 
water  below  the  surface  by  cutting  through  to  the  water- 
bearing stratum,  and  forming  a  conduit  for  it  to  pass  off.  This 
is  the  most  difficult  part  of  draining  operations. 


(Firr.  17.) 


In  order  to  show  the  nature  of  the  difficulty,  and  the  most 
common  methods  of  remedying  it,  let  us  suppose  that  Fig.  17 
is  a  section  of  a  piece  of  land  :  a  the  high  land,  d  a  swamp, 
which  may  be  produced  by  one  or  all  of  the  water-bearing 
strata  a  g  h,  which  crop  out  at  b  c,  and  produce  wetness 
along  the  surface  below.  The  water  in  A,  meeting  with  the  rock 
f,  rises  up  at  e  d.  The  land  from  6  to  c  may  be  drained 
by  a  ditch  at  b,  conducting  away  the  water  at  the  point 
where  it  reaches  the  surface.  The  land  between  c  and  d 
may  be  drained  by  the  ditch  c.     But  as  the  water-bearing 


260  ,  IMPROVEMENT  OF  THE  SOIL. 

Stratum  h  meets  with  resistance  at  f,  open  drains  must  be 
sunk  at  d  and  c,  to  conduct  it  off  into  some  stream,  in  or- 
der to  deprive  the  whole  of  superabundant  water.  It  is  not 
often  that  more  than  one  water-bearing  stratum  crops  out, 
and  the  most  important  point  is  to  determine  the  cause  of 
the  wetness,  in  order  to  save  time  and  expense  in  conducting 
it  off. 

Necessity  of  draining.  The  necessity  and  importance  of 
draining  wet  grounds,  may  be  rendered  evident  by  the  fol- 
lowing considerations. 

1.  An  excess  of  water  or  moisture  prevents  the  ploughing 
and  pulverizing  of  the  soil  until  late  in  the  season,  and  when 
the  attempt  is  finally  made,  it  can  but  imperfectly  succeed  ; 
hence  the  manures,  not  being  properly  incorporated  with  the 
soil,  are  deprived  of  their  effect  upon  the  roots.  The  crop  is 
checked  and  is  liable  to  be  injured  by  early  frosts. 

2.  An  excess  of  moisture  prevents  the  process  of  decay,  or 
the  decomposition  of  the  organic  matters  in  the  soil,  and  thus 
cuts  off  a  regular  supply  of  food.  This  effect  is  exemplified 
in  peat-swamps,  where  the  vegetable  matters  being  prevented 
from  decay  by  water,  accumulate  in  large  quantities,  to  the 
depth  often  of  20  feet,  and  form  peat. 

3.  Lands  which  have  an  excess  of  water,  often  become  dry 
and  compact  in  seasons  of  drought.  The  roots  are  thus  not 
only  prevented  from  penetrating  the  soil  and  from  extending 
themselves  freely  in  all  directions,  but  the  influence  of  the 
air,  and  of  the  dew,  which  are  so  important  in  dry  weather, 
are  almost  wholly  excluded  from  them.  Hence  such  soils, 
especially  if  they  are  stiff  clays,  suffer  as  much  from  drought 
as  from  excess  of  moisture. 

4.  When  the  roots  of  plants  extend  into  a  wet  soil,  the 
food  is  too  much  diluted,  or  is  not  prepared  in  sufficient 
quantities  to  ensure  a  healthful  and  vigorous  growth.  Leaves 
and  ill-formed  shoots  will  sometimes  be  abundant,  instead  of 
flowers  and  fruit.     There  are  a  iew  plants  which  will  flourish 


REASONS  FOR  DRAINING.  261 

well  in  a  wet  soil,  but  not  one  in  ten  of  those  cultivated  by 
the  farmer.  The  following  table  shows  the  proportion  of 
useless  and  useful  plants  on  different  soils.  Whole  number 
of  plants  are,  in 


Wet  meadows 

30, 

useful  4, 

useless  26. 

Dry  meadows 

38, 

1        "       ^, 

"       30. 

Moist  meadovv's 

42, 

"     17, 

«       25. 

5.  An  excess  of  water  injures  and  destroys  the  fibrous  por- 
tions of  the  roots,  or  spongelets,  by  means  of  which  nourish- 
ment is  received.  This  effect  takes  place  always  when  the 
water  becomes  stagnant  and  putrescent,  as  it  is  liable  to  be- 
come, when  the  land  is  level  and  the  sub-soil  retentive.  In 
some  cases  the  tissue  is  decomposed,  and  the  joints  of  the 
stem  separated.  In  others,  the  plant  rots  ofT  at  the  ground, 
especially  if  there  is  little  light  and  heat. 

6.  An  excess  of  water  excludes  the  influence  of  heat  and 
air,  two  indispensable  agents  to  the  growth  of  plants.  De 
Condolle  regards  the  influence  of  stagnant  water  about  the 
neck  of  plants,  as  operating  simply  to  exclude  the  oxygen  of 
the  air  ;  but  Lindley  more  properly  attributes  the  injury  to 
the  low  temperature  of  the  soil,  in  which  water  is  suffered  to 
accumulate. 

7.  Experience  shows  that  however  well  a  soil  may  be  con- 
stituted in  its  mineral  ingredients,  and  however  rich  it  may 
be  in  humus  or  geine  and  salts,  no  cultivated  crop  will  flour- 
ish well  unless  the  surface  of  the  soil,  and  the  soil  itself  is 
made  dry  during  the  growth  of  the  crop,  and  when  required 
to  be  worked  by  the  plough  or  the  hoe. 

"It  is  because  of  the  danger,"  says  Lindley,  "of  allowing 
any  accumulation  of  water  about  the  roots  of  plants,  that 
drainage  is  so  very  important.  In  very  bibulous  soils  this 
contrivance  is  unnecessary ;  but  in  all  those  which  are  tena- 
cious, or  which,  from  their  low  situation,  do  not  permit  su- 
22* 


26'2  IMPROVEMENT  OF  THE  SOIL 

perfluous  water  to  filter  away  freely,  such  a  precaution  is  in- 
dispensable."    Hence  the 

Utility  of  draining  must  be  evident  to  every  farmer.  For 
a  system  of  draining,  rightly  conducted,  will  not  only  remedy 
the  evils  above  described,  but  will  save  much  time  and  labor 
in  the  cultivation  of  the  crop  ;  two  weeks,  at  least,  will  be 
gained  in  the  getting  in  and  ripening  of  it.  The  product 
will  be  one  third  greater,  and  one  third  of  the  labor  saved 
in  the  tillage.  "  An  outlay  of  15  or  20  dollars  per  acre," 
says  Judge  Buel,  "  has  often  repaid,  by  extra  product  of  the 
reclaimed  land,  in  two  or  three  seasons."  In  addition  to 
these  advantages,  large  portions  of  barren  land,  in  many 
(portions  of  the  country,  may,  by  this  method,  be  reclaimed 
;and  rendered  productive.  We  know,  from  actual  observa- 
tion, that  some  of  the  most  valuable  lands  in  Massachusetts, 
now  lie  entirely  waste,  in  the  form  of  peat-meadows  and 
•swamps,  to  the  cultivation  of  which  it  is  for  the  highest  inter- 
est of  every  farmer  to  devote  his  immediate  efforts. 

II.  Irrigation.  Water,  as  we  have  seen  p.  93,  is  essen- 
tial to  the  growth  of  plants,  both  because  it  furnishes  them 
food,  and  because  it  is  the  vehicle  through  which  soluble 
matters  are  conveyed  into  the  vegetable  organs. 

We  know  that  plants  will  not  flourish  in  a  soil  which  is 
saturated  with  water ;  and  we  also  know,  on  the  other  hand, 
that  when  the  soil,  without  being  chemically  dry,  contains  so 
little  moisture  as  to  appear  dry,  vegetables  will  wither  and 
die.  The  question  to  decide  is,  what  amount  is  most  con- 
genial to  the  same  species  at  different  periods  of  their  growth  ? 

1.  It  may  be  taken  as  a  general  rule,  that  the  proper  time 
to  water,  is  when  the  soil  is  deprived  of  moisture  to  such  a 
depth,  that  the  plants  begin  to  languish  and  lose  their  leaves. 
The  juices  then  become  thickened,  and  the  transpiration  is 
nearly  suspended  ;  hence  the  plant  will  hasten  to  perfect  its 
ilowers  and  fruit,  which  will  be  incomplete  and  poor.     The 


BY  IRRIGATION.  263 

effect  of  water,  at  such  a  period,  is  to  dilute  the  sap  and  to 
furnish  the  means  of  transpiration ;  for  all  the  excess  of  wa- 
ter, taken  up  by  the  roots,  is  thrown  off  by  the  leaves. 
Hence  the  quantity  transpired  depends  upon  that  imbibed. 

2.  During  the  rest  of  plants  in  the  winter  of  northern  cli- 
mates, and  the  dry  season  under  the  tropics,  but  a  small 
quantity  of  water  is  required,  because  the  plants  do  not  trans- 
pire it.  Excess  of  moisture  at  such  seasons,  often  distends 
the  vessels  and  exposes  them  to  injury  by  the  frosts  of  spring. 
No  more  water  should  be  supplied  than  is  taken  up  by  the 
capillary  attraction  of  the  soil. 

3.  It  is  during  the  growth  of  plants,  and  when  their  leaves 
are  fully  matured,  that  the  greatest  quantity  of  water  is  re- 
quired. The  young  leaf  tranpsires  much  more  in  proportion 
to  its  surface  than  when  fully  matured,  and  hence  requires  a 
greater  quantity  to  be  absorbed  by  the  roots  ;  but  when  the 
leaves  grow  old,  their  cuticle  hardens,  and  the  apertures 
through  which  the  water  passes  off,  gradually  become  closed 
up ;  hence,  water  should  be  supplied  to  plants  abundantly 
when  they  first  begin  to  grow,  and  should  be  diminished  as 
they  grow  older.  During  the  ripening  of  the  succulent  fruit, 
plants  require  the  least  quantity ;  and  if  a  large  amount  is 
supplied  at  that  season,  the  fruit  may  be  plumper,  but  will 
loose  much  in  quality.  Strawberries  niay  be  increased  in 
size,  by  flooding  their  beds  with  water  during  the  period  of 
ripening,  but  they  lose  their  flavor,  and  become  insipid. 

It  will  be  perceived,  that  this  mode  of  improvement  is  of 
limited  extent  unless  in  case  of  green  houses  and  gardens.  It 
is  applicable  chiefly  to  light  sandy  soils.  Heavy  argillaceous 
soils  are  never  benefited  by  it.  When  dry  soils  are  situated 
in  the  vicinity  of  streams  or  Artesian  wells,  water  may  be 
^  brought  on  to  them  with  highly  beneficial  effects.  The  char- 
acter of  the  water  for  irrigation  upon  dry  lands,  is  a  point  of 
considerable  importance.  Water  from  a  running  stream  is 
vastly  superior  to  that  from  wells  or  springs,  and  the  farther 


264 


IMPROVEMENT  OF  THE  SOIL. 


the  water  has  run,  before  it  reaches  the  place  where  it  is 
taken  on  to  the  land,  the  more  remarkable  its  effects.  This 
is  due  to  two  causes  ;  1.  It  obtains  a  larger  quantity  of  gas- 
seous  bodies  such  as  oxygen  and  ammonia ;  and  2.  it  has  been 
shown,  that  water  from  streams  contains  crenic  and  apocrenic 
acids  often  combined  with  silica,  and  also  other  salts,  which 
it  has  dissolved  out  of  the  soil  or  rocks,  as  it  has  passed  over 
them. 

(1)  The  first  effect  of  water,  when  made  to  flow  over  the 
soil  by  this  process,  is  to  soften  it  and  render  it  more  permea- 
ble to  the  roots  of  plants,  and  to  the  air. 

(2)  Water  acts  still  further  in  dissolving  out  the  food,  and 
producing  those  chemical  changes  which  must  take  place  in 
the  manures,  before  they  are  fitted  for  nourishment. 

Care  should  be  taken,  not  to  apply  water  so  often  as  to 
keep  the  soil  in  a  state  of  paste,  in  which  case,  the  plant  may 
increase  in  size,  but  the  products  will  be  loose  and  spongy  in 
texture,  and  vapid  in  taste.  There  is  danger  too,  of  favoring 
the  growth  of  rushes  and  other  wild  grasses,  which  will  take 
the  place  of  the  more  valuable  ones. 

Another  caution  should  be  given  on  this  subject,  particu- 
larly applicable  to  garden  plants ;  upon  which  surface- water- 
ing is  sometimes  practised  during  the  dry  season.  The  effect 
of  thus  pouring  water  around  plants,  especially  in  the  heat  of 
the  day,  is  to  render  the  soil  compact  and  heavy  ;  thus  pro- 
ducing the  very  evil  which  it  is  intended  to  remedy.  It  ex- 
cludes the  air  and  the  water  which  it  contains  from  the  roots. 
If  surface-irrigation  is  ever  practised  on  garden  vegetables,  it 
should  be  done  at  night. 

Meadows  seem  to  be  most  benefited  by  irrigation  in  our 
climate,  although  we  know  that  in  some  countries  as  Egypt, 
it  is  practised  upon  all  kinds  of  soil,  and  for  every  species  of  f 
crop.  In  the  vicinity  of  Liegen  (Germany),  according  to 
Liebig,  from  three  to  five  perfect  crops  of  hay  are  annually 
produced  upon  the  same  meadow,  by  covering  the  fields  with 


FALLOW  CROPS  AND  NAKED  FALLOWS.        ^65 

river  water  in  the  spring.  **This  is  found  to  be  of  such  ad- 
vantage, that  supposing  a  meadow,  not  so  treated,  to  yield 
1,000  lbs  of  hay,  then  from  one  thus  ivatered,  4,500  lbs  are 
produced,"  an  increase  of  more  than  400  per  cent. 

The  practice  of  inundating  meadows  during  the  winter,  is 
recommended  both  by  Chaptal  and  Davy.  The  latter  found 
that  when  the  thermometer  stood  at  29°  F.  above  the  ice,  it 
was  43°  below  it ;  hence,  the  roots  of  grasses  are  kept  from 
fi"eezing,  and  the  whole  plant  remains  in  a  green  and  vigor- 
ous state  during  the  cold  season.  This  practice,  in  this  coun- 
try, is  too  much  confined  to  peat  meadows,  where  the  object 
is  not  to  defend  the  herbage,  but  to  prevent  the  frost  from 
rendering  the  peat  light  and  spongy. 

Sect.  3.  Improvement  of  the  Soil  hy  Fallow  Crops,  and  hy 
turning  in  Green  Crops, 

I.  Fallow  crops.  "  The  fallow  time,"  says  Liebig,  "  is  that 
period  of  culture  during  which  land  is  exposed  to  a  progres- 
sive disintegration  by  means  of  the  influence  of  the  atmos- 
phere, for  the  purpose  of  rendering  a  certain  quantity  of  alka- 
lies capable  of  being  appropriated  by  plants." 

By  "  fallow  crops  "  is  meant  the  raising  of  some  crop  on 
green-sward  while  the  turf  is  decaying,  instead  of  allowing 
the  land  to  remain  a  naked  fallow  during  this  process. 

The  object  then  of  fallows,  is  to  procure  the  decay  of  vege- 
table matters,  and  the  abstraction  of  alkalies  from  the  mineral 
portions  of  the  soil. 

Naked  fallows  accomplish  both  of  these  objects,  and  have 
been  long  practised  both  in  this  country  and  in  England. 
The  practice  with  us  has  been  to  plough  up  grass  lands  in 
June  or  July,  and  after  cross-ploughing  and  harrowing,  to 
sow  with  winter  grain  in  September  or  October.  In  Eng- 
land, the  land  was  formerly  ploughed  in  the  fall,  and  worked 
over  during  the  following  summer.  In  both  cases  one  crop 
is  lost ;  but,  though  naked  fallows  answer  the  intended  pur- 


266  IMPROVEMENT  OF  THE  SOIL. 

pose  tolerably  well,  they  are  now  abandoned  by  every  intelli- 
gent farmer  on  both  sides  of  the  water  ;  with  the  exception 
perhaps  of  wet  stiff  clays,  which  are  ameliorated  by  exposing 
the  naked  furrows  to  the  frosts  of  winter.  The  evils  of  the 
system  are  more  than  equivalent  to  the  benefits.  The  labor 
is  much  increased,  one  crop  is  lost,  and  the  vegetable  matters 
are  dissipated,  by  their  exposure  to  the  air  during  the  pro- 
cess of  working  the  land. 

Fallow  crops,  on  the  other  hand,  avoid  these  evils,  and  se- 
cure greater  benefit  both  to  the  soil  and  the  crop. 

Process.  To  prepare  the  soil  for  a  fallow  crop,  all  that  is 
needed  is  to  plough  the  green-sward  and  roll  it  down  ;  then, 
after  harrowing  thoroughly,  the  seed  should  be  sown  upon 
the  inverted  furrows,  either  in  the  spring  or  fall.  If  the  land 
is  stiff  and  wet,  the  autumn  is  preferable ;  if  light  and  dry, 
the  spring  is  the  best  season. 

The  utility  of  fallow  crops,  instead  of  naked  fallows,  may 
be  shown  by  reference  to  the  influence  of  growing  vegetables 
upon  the  soil.  The  elimination  of  alkalies  and  decay  of 
vegetable  matter  are,  as  we  have  said,  the  only  objects  of 
fallows. 

It  may  easily  be  shown,  that  both  of  these  ends  are  much 
belter  attained  by  tilling  the  fallow  land ;  for, 

1.  The  alkalies  are  furnished  in  greater  abundance  by  this 
process.  It  matters  not  whether  the  land  is  covered  by  woods, 
or  with  some  crop  which  will  take  up  but  few  alkalies,  such 
as  potash  and  phosphates.  Now  it  is  found  that  several  legu- 
minous plants  will  grow  upon  a  soil,  and  will  abstract  from  it 
but  a  minute  portion  of  alkalies.  The  "  Windsor  bean  {vi- 
ciafaba)  contains  no  free  alkalies,  and  only  one  per  cent,  of 
the  phosphates  of  lime  and  magnesia."  [Ein/iof.)  "  The 
kidney  bean  (phaseolus  vulgaris)  ^coni^ms  only  traces  of  salts." 
(Braconnot.)  "  The  stem  of  lucern  (mcdicago  sativa)  con- 
tains only  0.83  per  cent.,  that  of  the  lentil  (crvnni  lens)  only 
0.57  of  phosphate  of  lime  with  albumen."  (Cromc.) 


UTILITY  OF  FALLOW  CROPS.  267 

''Buckwheat,  dried  in  the  sun,  yields  only  0.681  per  cent, 
of  ashes,  of  which  0.09  parts  are  soluble  salts"  [Lichig) ; 
hence,  these  plants  with  others,  have  been  called  fallow  crops. 
It  will  be  perceived,  that  the  alkalies  which  the  oxygen  and 
carbonic  acid  of  the  air  are  eliminating  from  the  soil,  will  be 
increased  in  this  case,  because  the  roots  of  the  crop  will  per- 
mit these  agents  to  act  with  greater  power. 

The  power  of  growing  plants  to  decompose  the  rocks,  and 
to  eliminate  alkalies,  has  already  been  frequently  referred  to  : 
and  as  but  a  small  quantity  of  alkali  is  removed  by  the  fallow 
crop,  the  amount  in  the  soil  is,  upon  the  whole,  increased. 

2.  It  is  further  evident,  that  the  roots  leave  in  the  soil  nearly 
as  much  vegetable  matter,  as  is  carried  away  in  the  stalks  and 
grain.  This  deficiency  is  made  up  by  the  influence  of  grow- 
ing plants  upon  the  humus  of  the  soil.  There  is  little  doubt, 
but  that  decay  proceeds  much  more  rapidly  when  the  soil  is 
tilled,  than  when  it  is  not ;  and  the  reason  is,  the  galvanic 
agency  of  the  roots  and  the  facility  which  they  offer  for  the 
introduction  of  air  and  water  by  loosening  the  soil,  tend  pow- 
erfully to  hasten  the  decay  of  humus,  or  to  convert  the  vege- 
table matters  into  vegetable  food.  The  fermentation  of  the 
sod  will  be  more  complete  when  it  is  turned  in  deep,  and  the 
gaseous  products  will  be  retained  by  the  superincumbent 
earth  ;  hence  we  may  draw  an  argument  for  deep  ploughing, 
and  for  letting  the  sod  remain  until  it  has  completely  passed 
through  the  fermenting  process. 

II.  Turning  in  green  crops.  The  turning  in  of  green 
crops,  has  long  been  a  reputed  source  of  rendering  barren 
soils  fertile.  It  is  well  suited  to  any  soil  which  requires  either 
to  be  rendered  lighter,  or  to  be  filled  with  veoretable  matter 
and  salts.  Light  sandy  soils,  such  as  pine-barrens  and  loams, 
which  have  been  exhausted  by  a  long  course  of  cropping 
without  manuring,  are  most  benefited,  while  stiff  clays  are 
rendered  much  warmer,  and  more  friable. 

Processes.      1.  Green  crops  may  be  sown  for  the  purpose 


268  IMPROVEMENT  OF  THE  SOIL. 

and  turned  in,  either  before  the  seed  ripens  (in  which  case  two 
crops  may  be  turned  in  the  same  season),  or  after  the  crop  is 
nearly  ripe.  In  the  first  case,  before  the  ripening  of  the 
seed,  the  plant  derives  most  of  its  substance  from  the  atmos- 
phere ;  but  when  the  seeds  are  maturing,  it  draws  directly 
upon  the  matters  in  the  soil.  Some  experiments  have  been 
made  to  decide  which  course  is  best,  and  they  incline  to  the 
dry  crop.  If  but  one  crop  is  to  be  added  to  the  soil,  this 
would  be  the  best  process,  because  it  adds  a  greater  amount 
of  salts  and  humus ;  but  two  green  crops  are  better  than  one 
dry  crop.  Buckwheat  and  oats  answer  well  for  this  purpose. 
2.  But  the  better  course  is  to  save  the  crop  by  sowing  clover 
with  other  grain,  and  the  next  spring  turn  it  in  ;  and,  having 
rolled  it  down,  plant  directly  upon  the  furrows  with  potatoes 
and  corn.  The  surface,  then,  should  be  tilled  with  the  cul- 
tivator or  hoe,  so  as  not  to  disturb  the  sod.  Some  recom- 
mend, in  this  case,  to  spread  a  light  covering  of  compost- 
manure,  lest  the  soil  should  be  too  much  exhausted  by  the 
crop. 

Now  it  is  found  that  the  quantity  of  vegetable  matters 
added  to  the  soil  by  this  process,  will  exceed  12  tons  to  the 
acre.  Elias  Phinney,  Esq.  of  Lexington,  has  actually  weighed 
the  vegetable  matter  in  a  cubic  foot  o^ green  sod,  from  which 
he  made  an  estimate  that  one  acre  contained  more  than  13 
tons  ! 

The  best  thne  for  turning  in  green  crops,  or  breaking  up 
green-sward  (unless  the  soil  is  a  stiff  clay),  is  the  spring  and 
early  part  of  summer;  because  the  sod  will  become  rotted 
before  winter,  and  will  not  afford,  as  it  otherwise  might,  a 
shelter  for  worms,  during  that  season,  ready  to  injure  the 
succeeding  crop. 

Theory.  The  theory  of  this  process  is  exceedingly  simple. 
It  is  evident  that  what  is  taken  from  the  soil  must  be  returned 
to  it,  or  the  land  will  be  impoverished.     We  have  seen  that 


TURNING  IN  OF  GREEN  CROPS.  269 

salts  and  geine  are  removed.     This  process  simply  restores 
them. 

1.  The  green  crop  being  buried  deeply  in  the  ground, 
soon  begins  to  ferment  and  decay  ;  a  large  quantity  of  or- 
ganic food  is  thus  added  to  the  soil.  But  humus  or  geine  is 
not  the  only  substance  required  by  plants.  They  must  have 
alkalies. 

2.  These  are  supplied  in  part  by  the  influence  of  the  at- 
mosphere, the  ordinary  process  of  disintegration.  But  this 
is  trifling  compared  with 

3.  The  galvanic  effect  of  the  living  plant.  The  agency  of 
growing  plants  has  hitherto  been  overlooked  in  this  connec- 
tion. As  the  roots  form  a  galvanic  battery  with  the  soil,  they 
become  the  most  powerful  decomposing  agents.  Now  we 
know  that  the  poorest  soils  (the  pine-barrens)  contain  a  large 
quantity  of  alkalies,  potash,  lime,  etc.  locked  up  in  the  rocks. 
These  are  drawn  into  the  organs  of  plants,  where,  as  soon  as 
covered  with  earth,  they  exist  in  a  fit  state  to  nourish  future 
crops.  If,  then,  we  can  make  a  plant  grow  at  all  upon  such 
soils,  we  can  render  them  fertile  by  turning  in  green  crops, 
and  thus  furnishing  the  requisite  amount  of  geine,  alkalies 
and  salts.  If  the  soil  is  too  barren  to  produce  plants,  a  small 
coating  of  ashes  will  give  a  start  to  the  green  crop,  and  then 
the  soil  may  soon  be  rendered  fertile. 

In  case  of  clayey  soils,  the  turning  in  of  green  crops  not 
only  restores  what  is  exhausted  by  tillage,  but  renders  the 
texture  much  better  fitted  for  the  roots  of  plants,  and  the  soil 
itself  a  better  retainer  of  heat. 

In  case  of  dry,  gravelly  soils,  the  additional  vegetable  mat- 
ter gives  the  power  of  absorbing  moisture  and  equalizing  the 
heat ;  hence,  it  protects  the  plant  from  the  extremes  of  dry 
and  wet  seasons. 

The  importance  of  this  mode  of  improvement  is  not  fully 
felt  by  our  farmers.  By  sowing  a  few  pounds  of  clover-seed 
with  his  grain-crops,  the  farmer  may  be  constantly  augment- 
23 


270  IMPROVEMENT  OF  THE  SOIL. 

ing  the  fertility  of  his  soil  without  the  loss  of  a  single  crop  ; 
and  even  if  his  lands  rest  a  year,  and  all  their  produce  is 
given  back  to  them,  they  will  more  than  return  it  in  a  few 
years,  by  the  larger  quantity  and  better  quality  of  their  pro- 
ductions. 

It  will  be  seen  that  fallow  crops  and  the  turning  in  of 
green  crops,  are  somewhat  similar  in  their  influence  upon  the 
soil.  The  object  in  both  cases  is  to  obtain  alkalies  or  salts 
and  geine.  Fallow  crops  yield  mostly  the  former,  green 
crops  principally  the  latter ;  and  by  both  processes  taken  to- 
gether, a  soil  may  be  rendered  very  fertile,  without  the  addi- 
tion of  manures;  especially  for  crops  not  requiring  much 
nitrogen. 

Sect.  4.  Rotation  or  Interchange  of  Crops. 

Rotation  of  crops  is  to  cultivate,  successively,  on  the  same 
field,  crops  of  different  kinds  and  of  different  habits,  such  as 
common  grains,  roots  and  grasses. 

The  necessity  and  utility  of  an  interchange  of  crops  has 
been  ascertained  by  experience. 

1.  It  was  found  that  the  growth  of  annual  plants  was  ren- 
dered imperfect,  by  cultivating  them  on  the  same  soil  in  suc- 
cessive years;  and  that  a  greater  quantity  of  grain  would  be 
obtained  to  let  it  rest  for  a  season,  during  which  time  it 
seemed  to  regain  its  original  fertility. 

2.  It  was  also  observed  that  some  plants,  such  as  peas, 
flax  and  clover,  do  not  thrive  well  on  the  same  soil  until  after 
several  years ;  whilst  others,  such  as  tobacco,  rye,  oats  and 
Indian  corn,  may  be  cultivated  in  close  succession. 

3.  It  was  further  ascertained  by  experience,  that  one  class 
of  plants  improve  the  soil,  a  second  impoverish  it,  while  a 
third  class  exhaust  it. 

4.  To  keep  up  the  fertility,  manure  has  always  been  em- 
ployed.    But  however  much  a  soil  may  be  manured,  it  is 


REASONS  FOR  INTERCHANGE  OF  CROPS.        271 

well  established,  that  the  produce  of  many  plants  diminishes, 
when  cultivated  for  several  years  on  the  same  soil. 

5.  But  on  the  other  hand,  it  is  also  fully  settled,  that  when 
a  field  has  become  unfitted  for  one  species  of  grain,  it  is  not 
therefore  unfitted  for  another  ;  but  that  a  succession  of  plants 
will  flourish  well  without  the  addition  of  a  large  quantity  of 
manure;  hence  has  arisen  the  modern  system  of  rotation. 
It  now  becomes  a  question  of  the  first  importance  whether 
these  facts  can  be  so  explained,  as  to  aid  us  in  pointing  out 
the  best  system  of  rotation.  If  we  can  fully  ascertain  the 
causes  of  the  failure  of  the  successive  cultivation  of  the  same 
crop,  and  of  the  favorable  effects  of  rotation,  we  shall  be  pro- 
vided with  the  best  hints  for  constructing  a  proper  system. 
These  causes  are  to  be  found  in  the  structure  of  plants,  in 
their  composition,  and  in  the  influence  of  the  matters  which 
they  excrete  by  their  roots. 

I.    The  structure  of  plants,  such  as  their  roots,  stalks  and 
leaves,  afford  one  important  reason  for  the  rotation  of  crops. 
Each  family  of  plants  have  similar  roots,  leaves,  etc.     Their 
action  upon  the  soil  is  therefore  similar.     The  spindle  roots, 
for  example,  like  the  carrot  and  beet,  extend  their  roots  deeply 
into  the  soil,  while  the  common  grains  lie  near  the  surface. 
Clover  and  some  of  the  grasses  penetrate  to  a  considerable 
depth,  and  branch  out  in  all  directions  ;  hence,  when  one  kind 
of  crop  is  planted   in  the  same  soil  for   several  successive 
years,  the  effect  both  mechanically   and  chemically  is  the 
same.     Chaptal  supposes  that  the  roots  exhaust  only  those 
portions  of  the    soil    which    are    in    contact    with    them, 
and  hence  similar  roots  exhaust  the  soil  in  the  same  parts; 
but  this  effect  could  not  take  place  when  the  land  is  ploughed 
between  each  crop,  though  it  might  apply  to  trees.     This 
theory  is  wholly  set  aside  by  the  fact,  that  the  roots  form  a 
galvanic  battery  with  the  soil  ;  and,  as  in  all  galvanic  circles, 
the  matter  would  be  transferred  from  some  distance  around, 
so  that  the  plant  could  stand  in  no  need  of  food,  provided  it 


272  IxMPROVEMENT  OF  THE  SOIL. 

were  surrounded  by  substances,  which  will  keep  up  with  it, 
the  vigor  of  the  galvanic  action. 

In  addition  to  the  mechanical  effect  upon  the  soil,  we 
would  suggest  whether  similar  roots  may  not  form  with  the 
soil  similar  galvanic  circles  of  similar  power  and  mode  of  ac- 
tion, and  that  the  interchange  of  crops  changes  this  action  or 
restores  its  activity.  We  know  that  different  metals  require 
different  substances  to  excite  the  voltaic  currents,  and  that 
rest  or  a  change  of  materials  will  restore  the  action  of  a  bat- 
tery, when  its  power  is  exhausted.  The  reason  why  some 
plants  exhaust  the  soil  more  than  others,  is  partly  due  to  their 
structure.    In  this  respect  plants  are  divided  into  three  classes. 

1.  The  culmiferous  plants,  so  called  from  culm,  the  stalk, 
which  is  usually  hollow  and  jointed  in  order  to  afford  support 
both  to  the  leaves  and  seeds.  Wheat,  barley,  oats,  rye,  In- 
dian corn,  tobacco,  cotton,  flax,  hemp  and  the  grasses,  are 
of  this  class.  All  of  them,  save  some  of  the  grasses,  are 
termed  exhausters  of  the  soil,  and  in  all  cases  exhaust  it 
more  during  the  ripening  of  the  seeds  than  during  any  other 
period  of  their  growth.  Flax  and  hemp  are  the  most  ex- 
hausting crops,  because  their  leaves  are  small,  and  hence  but 
a  small  quantity  of  their  substance  can  be  obtained  from  the 
atmosphere.  They  also  return  but  a  small  quantity  of  mat- 
ter to  the  soil,  in  the  form  of  stubble  and  roots. 

The  smaller  grains  rank  next  in  their  power  of  exhausting 
the  soil,  because  their  leaves  are  narrow  and  roots  small. 
They,  however,  return  more  to  the  soil  in  the  form  of  stubble. 

Indian  corn,  tobacco  and  rice,  have  larger  leaves,  and  de- 
rive more  of  their  substance  from  the  atmosphere.  The  roots 
of  culmiferous  plants,  being  fibrous,  do  not  penetrate  and  di- 
vide the  soil  so  perfectly  as  those  of  the  next  family  ;  and,  on 
this  account,  do  not  leave  the  soil  in  so  good  a  condition  for 
succeeding  crops. 

Von  Thaer  has  attempted  to  determine  experimentally 
the  different  degrees  in  which  different  kinds  of  grain  exhaust 


REASONS  FOR  INTERCHANGE  OF  CROPS.        273 

the  soil.  If  wheat  exhaust  four  degrees,  rye  will  exhaust  but 
three  and  a  quarter  degrees,  barley  but  two  and  one  fourth, 
and  oats  but  one  six-tenth  degrees  per  bushel  of  the  products. 

2.  The  leguminous  plants,  such  as  peas,  beans  and  other 
pulse,  exhaust  the  soil  much  less  than  the  preceding  class, 
because  their  leaves  are  more  numerous,  and  their  stalks 
more  vigorous.  They  are  therefore  able  to  derive  more 
nourishment  from  the  atmosphere,  while  their  roots  divide 
the  soil  more  perfectly,  and  leave  it  in  a  better  state  for  suc- 
ceeding crops  ;  hence  they  have  been  said  to  impoverish  the 
soil. 

3.  Root  crops,  such  as  potatoes,  turnips,  beets,,  carrots, 
onions,  cabbages  and  clover,  exhaust  the  soil  less  than  either 
of  the  preceding  classes,  and  are  hence  called  ameliorating 
crops.  This  class  are  provided  with  large  fleshy  and  porous 
leaves,  by  means  of  which  they  obtain  a  large  portion  of  their 
nourishment  from  the  atmosphere,  in  the  form  of  ammonia, 
carbonic  acid  and  water.  As  these  plants  are  seldom  culti- 
vated for  their  seeds,  they  rarely  mature  them  the  first  season  ; 
hence  they  derive  but  little  nutriment  from  the  soil.  Theii 
bulbous  or  tap  roots  divide  the  soil  more  perfectly,  and  pre- 
pare it  for  succeeding  crops. 

The  reason  why  some  plants  foul  the  soil  more  than  oth- 
ers is  also  due  to  their  structure.  Plants  which  have  small 
leaves,  permit  the  weeds  to  grow,  and  to  appropriate  to  them- 
selves the  nutriment  which  belongs  to  the  crop.  They  also 
exhaust  the  soil  most,  while  plants  with  broad  leaves  cover  up 
and  prevent  the  weeds  from  growing,  and  these  also  exhaust 
the  soil  the  least. 

II.  The  composition  of  plants  explains  the  reason  why 
some  plants  exhaust  the  soil  more  than  others,  and  hence 
may  aid  us  in  forming  a  judicious  system  of  rotation. 

We  have  seen,  p.  169,  that  different  plants  require  different 
quantities  and  kinds  of  alkalies  and  salts,  such  as  potash,  soda, 
ammonia,  magnesia,  etc.  to  complete  their  growth  ;  and  when 
23* 


274  IMPROVEMENT  OF  THE  SOIL. 

we  examine  their  ashes,  we  find  that  some  species  require  phos- 
phate of  magnesia  or  phosphates,  and  others  potash,  and  oth- 
ers still,  substances  rich  in  nitrogen,  such  as  nitre  and  ammo- 
nia. We  have  also  seen  that  these  substances  exist  in  the  soil, 
in  small  quantities,  and  hence  are  liable  to  be  removed  by  a 
continued  course  of  cropping. 

1.  If  we  take  100  parts  of  wheat  straw  they  will  yield  15.5 
parts  of  ashes.  The  same  quantity  of  barley  straw  will  yield 
8.54  parts,  and  100  parts  of  oat  straw  only  4.42  parts.  The 
ashes  of  all  are  of  the  same  composition.  The  principal  salts 
are  phosphates,  especially  phosphate  of  magnesia,  hence  it  is 
evident  "  that  upon  the  same  field,  which  will  yield  only  one 
harvest  of  wheat,  two  crops  of  barley,  and  three  of  oats  may 
be  raised,"  and  this  is  due  to  the  different  quantity  of  phos- 
phates, which  they  derive  from  the  soil,  and  if  wheat  suc- 
ceed wheat,  these  substances  will  be  sooner  taken  from  it. 

2.  It  is  evident  that  if  two  plants  grow  beside  each  other  or 
in  succession  on  the  same  soil,  they  will  injure  each  other  if 
they  withdraw  the  same  alkalies  from  it;  hence  wild  chamomile 
and  Scotch  broom  impede  the  growth  of  corn,  because  they 
yield  from  7  to  7.43  per  cent,  of  ashes,  which  contain  -{^  of 
carbonate  of  potash,  the  very  alkali  which  the  corn  requires. 
If  these  plants  succeed  each  other  the  same  injury  will  be 
done. 

3.  But  on  the  other  hand  if  two  plants  grow  beside  each 
other  or  in  succession,  which  require  different  quantities  of 
any  alkali  for  their  development,  they  will  flourish  well ; 
hence  if  a  soil  contain  potash,  wheat  and  tobacco  may  suc- 
ceed each  other  although  both  are  exhausting  crops,  that  is, 
both  require  potash  ;  yet  they  require  different  quantities  of 
phosphates  ;  thus  for  example,  10,000  parts  of  the  leaves  of  to- 
bacco-plant contain  16  parts  of  phosphate  of  lime,  8.8  parts 
silica,  and  no  magnesia ;  whilst  an  equal  quantity  of  wheat 
straw  contains  47.3  parts,  and  the  same  quantity  of  the  grain 
of  wheat  99.45  parts  of  phosphates.    {De  Saussure.)    Hence 


REASONS  FOR  INTERCHANGE  OF  CROPS.        275 

the  quantity  of  phosphates  extracted  from  the  soil  by  the  same 
weights  of  wheat  and  tobacco  must  be  as  97.7  to  16,  and 
when  the  difference  is  so  great  as  this,  the  plants  may  suc- 
ceed each  other. 

4.  Now  if  we  examine  what  are  called  the  ameliorating 
crops,  we  shall  find  that  they  contain  a  very  small  quantity  of 
alkalies  or  of  substances  containing  nitrogen,  or  of  both.  Thus 
the  leguminous  plants  contain  only  traces  of  salts,  p.  266,  and 
hence  they  do  not  injure  the  crops  of  corn  which  are  sowed 
with  or  succeed  them.  The  root  crops  require  still  less  of 
these  alkalies  and  salts,  and  hence  their  ameliorating  effects. 

5.  If  we  observe  the  rotation  which  is  carried  on  in  na- 
ture, for  example,  that  pine  trees  succeed  oaks,  and  oaks 
pines,  and  examine  their  ashes,  we  shall  find  the  reason  of  it. 
*'  One  thousand  parts  of  the  dry  leaves  of  the  oak  yield  55 
parts  of  ashes  of  which  24  parts  consist  of  alkalies  soluble 
in  water,"  while  the  same  quantity  of  pine  leaves  gives  only 
59  parts  of  ashes  which  contain  4.6  parts  of  soluble  salts, 
{De  Saussure);  and  generally  those  trees  whose  leaves  are 
renewed  annually,  require  from  6  to  10  times  more  alkalies 
than  the  fir-tree  or  pine. 

6.  It  must  be  evident,  without  further  examination,  that 
the  causes  of  the  failure  of  crops  when  cultivated  successive- 
ly on  the  same  field,  and  the  reasons  for  rotation,  are  to  be 
found  in  the  kind  and  quantity  of  the  substances,  which  each 
species  of  plant  extracts  from  the  soil.  Some  agricultural 
writers  have  held  to  the  hypothesis,  that  each  species  of 
plant  requires  different  kinds  of  food,  and  when  it  has  ex- 
hausted its  specijic  food  from  the  soil,  another  species  will 
flourish  until  its  specific  food  is  exhausted.  We  may  learn 
from  the  above  examination  what  this  specific  food  is.  It  is 
the  alkali*  or  salt  which  the  plant  requires  for  its  develop- 
ment. 

It  should  be  remarked,  however,  that  as  one  alkali  may  be 
*  See  Liebig,  p.  216. 


276  IMPROVEMENT  OF  THE  SOIL. 

substituted  for  another  in  some  cases,  we  must  seek  still  fur- 
ther for  facts  and  principles,  fully  to  explain  the  reasons  for 
the  rotation  of  crops,  and  their  beneficial  effect. 

III.  The  excretions  toliich  the  roots  of  plants  deposit  in  the 
soil  have  been  regarded  by  some  as  the  most  satisfactory  mode 
of  explaining  the  effect  of  cultivating  the  same  crop  in  suc- 
cession on  the  same  field,  and  of  the  benefits  of  rotation.  Lie- 
big  considers  the  view  now  to  be  presented,  as  the  only  one 
deserving  "  to  be  mentioned  as  resting  on  a  firm  basis."  It 
is  the  theory  of  M.  De  Condolle,  "  who  supposes  that  the 
roots  of  plants  imbibe  soluble  matter  of  every  kind  from 
the  soil,  and  thus  necessarily  absorb  a  number  of  substances 
which  are  not  adapted  to  the  purposes  of  nutrition,  and  must 
subsequently  be  expelled  by  the  roots,  and  returned  to  the 
soil  as  excrements."  Now  as  excrements  cannot  be  assimi- 
lated by  the  plant  which  ejected  them,  the  more  of  these 
matters  the  soil  contains,  the  more  unfertile  must  it  be  for 
plants  of  the  same  species.  These  excrementitious  matters 
may,  however,  still  be  capable  of  assimilation  by  another  kind 
of  plants,  which  would  thus  remove  them  from  the  soil,  and 
render  it  again  fertile  for  the  first.  [Liehig.)  In  a  word, 
one  species  of  plants  excretes  by  its  roots  substances,  which 
are  poisonous  or  innutritions  to  plants  of  the  same  family,  but 
which  may  be  assimilated  by  plants  of  a  different  species. 

The  experiments  of  iV/«cmVePrmfeps  prove,  that  the  roots 
of  plants  do  expel  matters  which  cannot  be  converted  into 
any  of  their  component  parts.  Some  of  these  excrements  are 
of  a  gummy  and  resinous  character,  and  are  regarded  as  pois- 
onous ;  others,  are  compounds  of  carbon  and  are  nutritious. 
Liebig  supposes  that  these  excrements  are  not,  according  to 
De  Condolle,  derived  from  the  soil,  but  from  the  atmosphere  ; 
and  that  it  is  in  this  way  that  a  soil  receives  as  much  carbon 
from  the  plant  as  it  yields  to  it.  It  now  becomes  an  interest- 
ing  inquiry  what   state  this   excrementitious   matter  is  in, 


THEORY  OF  THE  INTERCHANGE  OF  CROPS.  277 

whether  it  is  already  fitted  to  nourish  other  species  of  plants, 
or  must  first  pass  through  some  chemical  change  1 

It  appears  that  the  excrementitious  matter  of  De  CondoUe 
is  matter  derived  from  the  soil,  and  is  not  fitted  to  nourish 
that  species,  but  may  be  indispensable  to  some  other  plant. 
It  is  undigested  matter,  and  resembles  the  undigested  excre- 
ments of  animals,  which,  though  unfitted  to  be  assimilated  by 
one  animal,  may  prove  nutritious  to  another. 

The  excrements  of  Macaire  Princeps  may  be  derived  from 
the  soil,  but  they  are  matters  formed  in  the  vegetable  organs. 
They  are  compounds  produced  in  consequence  of  the  trans- 
formations of  the  food,  and  of  the  new  forms  which  it  assumes 
by  entering  into  the  composition  of  the  vegetable  organs. 
They  are  not,  therefore,  supposed  capable  of  nourishing 
other  species  of  vegetables,  until  a  change  is  wrought  upon 
them.  This  change  is  effected  by  the  agency  of  the  atmos- 
phere, water,  etc.,  and  they  are  converted  into  humus. 

These  views  do  not  contradict  each  other  ;  both  may  be,  and 
doubtless  are  true ;  both  explain  why  it  is  that  after  wheat, 
wheat  will  not  flourish  so  well  on  the  same  soil,  and  why 
one  crop  must  succeed  another  to  keep  up  the  quantity  of 
produce. 

The  latter  theory,  however,  explains  the  fact  that  the  ex- 
crements of  some  plants,  affect  the  same  species  longer  than 
others ;  for  it  is  evident  that  the  time  required  for  the  decay 
of  the  excrements  may  depend  upon  their  nature,  quantity, 
and  the  composition  and  character  of  the  soil.  In  a  calcare- 
ous soil  it  would  be  rapidly  effected,  and  hence  it  is  found 
that  such  soils  admit  of  the  same  crop  after  the  second  year ; 
or  its  decay  may  be  effected  by  alkalies,  and  this  is  doubt- 
less one  of  the  good  effects  of  adding  these  substances  to  the 
soil.  But  when  the  soil  is  siliceous  or  argillaceous,  the  same 
crop  cannot  be  cultivated  with  advantage  until  the  fourth  or 
ninth  year.  Thus  for  example,  "  clover  will  not  flourish  in 
some  soils  oftener  than  once  in  six  years,  on  other  soils,  once 


278 


IMPROVEMENT  OF  THE  SOIL. 


in  twelve  years.  {Liebig.)  The  excrements  of  different 
plants  require  different  periods  to  effect  their  conversion  into 
humus  ;  the  excrements  of  flax,  peas  and  clover,  for  example, 
when  grown  on  argillaceous  soils,  require  the  longest  period 
to  effect  this  change. 

From  the  views  now  presented,  we  may  see  the  reason 
why  the  interchange  of  crops  produces  effects  so  highly  bene- 
ficial. It  is  because  the  cultivation  of  different  kinds  of 
plants  on  the  same  field,  enables  each  to  extract  certain  com- 
ponents of  the  soil,  which  are  necessary  to  it,  and  to  leave 
behind  or  restore  those  which  a  second  or  third  species  may 
require  for  its  growth,  and  perfect  development.  In  con- 
structing a  system  of  rotation,  therefore,  we  must  have  refer- 
ence to  the  structure  of  plants,  to  the  alkalies  and  salts 
which  each  species  of  plant  requires,  and  to  the  matters 
which  they  excrete  from  their  roots.  We  will  therefore  con- 
clude this  subject  with  a  series  of  rules  derived  both  from  ex- 
perience, and  from  the  views  now  presented. 

1.  Two  exhausting  crops  should  not  succeed  each  other  on 
the  same  field,  because  their  structure  is  similar,  and  they  de- 
rive similar  ingredients  from  the  soil. 

2.  Culmiferous,  leguminous  and  root  crops  should  alternate 
with  each  other,  because  their  structure,  composition  and  ex- 
cretions are  most  diverse,  and  the  least  injurious  to  each 
other.  If  the  first  crop  is  a  hoed  crop,  the  second  should  be 
a  grain  crop ;  although  two  hoed  crops  such  as  corn  and  po- 
tatoes, or  turnips,  are  better  than  two  grain  crops. 

3.  A  grain  crop  should  succeed  a  hoed  crop,  rather  than 
precede  it.  The  reason  in  this  case  appears  to  be,  that  the 
manures  can  be  more  perfectly  worked  into  the  soil  by  a  hoed 
crop,  and  the  soil  is  left  in  a  better  condition  for  grain. 
There  are,  however,  two  exceptions  to  this  rule.  1.  When 
clover  makes  one  crop  in  the  rotation,  it  is  found  that  wheat 
may  succeed  it  with  advantage,  because  they  require  different 
alkalies  or  salts,  and  the  roots  of  the  clover  prepare  the  soil  for 


ROTATION  SYSTEM.  279 

wheat  better  than  most  other  crops  ;  hence,  it  is  the  practice 
of  the  best  farmers  to  cut  their  clover  early,  and  turn  over  the 
sod  for  winter  wheat.  2.  A  grain  crop,  as  oats,  may  be  taken 
as  a  fallow  crop  previous  to  wheat  or  rye. 

The  following  will  be  found  a  good  system  of  rotation.  1. 
The  first  year,  beans,  potatoes  or  Indian  corn  with  manure.  2. 
The  second  year,  wheat,  rye,  barley  or  oats,  without  manure. 
3.  The  third  year,  roots,  such  as  turnips,  carrots  or  beets, 
with  deep  tillage  and  compost  manure.  4.  The  fourth  year, 
the  same  as  the  second  year,  with  clover  seed.  The  land 
should  be  smoothed  and  may  remain  in  clover  for  a  few  years, 
or  a  clover  crop  may  be  taken,  and  a  rotation,  commencing 
with  wheat  and  hoed  crops,  succeed  in  the  same  order. 

In  constructing  a  rotation  system,  however,  the  farmer 
should  consult  the  demand  for  the  articles  which  he  raises, 
and  the  character  of  his  soil,  as  a  different  system  is  required 
for  dry  and  wet  or  stiff  soils.  He  may  select  his  crops  at  pleas- 
ure, provided  he  do  not  violate  the  principles  already  suggest- 
ed. The  old  practice  ot  growing  the  same  crop  for  several 
years  upon  the  same  field,  if  adhered  to,  will  certainly  wear  out 
his  lands,  and  he  will  experience,  what  thousands  have  be- 
fore him,  the  sure  rewards  of  his  folly,  barrenness  of  his  lands, 
and  poverty  of  purse.  It  is  astonishing  that  farmers  have 
continued  the  practice  so  long.  It  would  seem  that  their  ob- 
servations of  what  is  constantly  going  forward  in  nature 
would  have  corrected  the  evil. 

Forests  are  frequently  alternating ;  hard  wood  succeeds 
pine ;  hemlock,  pine  and  cedar  succeed  hard  wood.  Rasp- 
berries and  strawberries  are  endowed  by  nature  with  roots  by 
which  they  change  their  location.  Natural  meadows  change 
their  grasses  gradually,  and  the  fact  is  so  general,  that  it  may 
be  regarded  as  a  law  of  nature  ;  change  of  plants  being  one 
of  the  means  which  nature  employs  to  keep  up  fertility,  or 
to  restore  her  exhausted  energies. 

A  good  rotation  system  forms  the  basis  of  good  husband- 


280  IMPROVEMENT  OF  THE  SOIL. 

ry.  Without  it,  the  soil  may  be  kept  fertile  by'the  addition  of 
great  quantities  of  manure  and  rest,  but  with  it,  time  and 
manure  are  economized,  the  soil  rendered  more  and  more 
fertile,  and  the  products  increasingly  more  valuable. 

Rotation  of  Jields.  Rotation  of  fields  is  next  in  impor- 
tance to  a  rotation  of  crops.  By  this  we  mean,  that  tillage, 
pasture  and  grass  land,  should  alternate  with  each  other. 
This  practice  is  in  opposition  to  the  very  common  one,  of 
devoting  a  certain  portion  of  the  farm  perpetually  to  tillage ; 
another  to  grass,  and  the  remainder  to  pasture.  Wherever 
it  is  practicable,  these  should  alternate,  and  the  same  reasons 
may  be  urged  as  for  a  rotation  of  crops.  Old  pasture  lands 
often  become  exceedingly  fertile  by  the  droppings  of  the  cattle 
and  may  be  cultivated  with  the  best  results,  while  tillage  and 
grass  lands  are  often  benefited  by  turning  them  into  pasture. 
In  many  parts  of  New  England  there  are  extensive  swamps 
which  may  be  cultivated,  and  made  the  most  valuable  lands. 
These  lands  are  now  either  wholly  waste,  or  used  only  as 
grass  lands. 

Sect.  5.  Root  Culture* 

Root  culture  is  not  only  an  important  means  of  improv- 
ing the  soil  in  a  rotation  system,  but  the  products  are  the 
most  valuable  means  of  feeding  and  fattening  cattle,  and  of 
producing  manure.  "  It  trebles"  says  Judge  Buel,  "  the 
am.ount  of  cattle-food,  and  doubles  the  quantity  of  manure. 
It  moreover  may  be  made  to  supply  a  large  amount  of  hu- 
man food." 

The  principal  roots  suited  to  our  climate,  are  the  potato, 
turnip,  carrot,  beet,  and  those  usually  cultivated  in  our  gar- 
dens. Of  these  the  potato  has  come  into  general  use.  The 
beet,  carrot  and  the  Swedish  turnip  are  the  most  profita- 
ble, both  as  to  their  influence  upon  the  soil,  and  for  the  value 
of  their  products.  The  English  turnip  is  very  valuable  for 
an  after-crop,  and  tends  to  increase  the  fertility  of  the  soil, 


UTILITY  OF  ROOT  CROPS.  281 

especially  if  cattle  and  sheep  are  turned  into  the  field,  and 
allowed  to  feed  upon  them.  This  means  of  fertility,  and  of 
producing  a  large  and  valuable  quantity  of  fall  or  after  feed, 
is  almost  wholly  neglected  by  our  farmers.  How  easy  it 
would  be,  after  wheat  or  winter  rye,  to  sow,  say  about  the 
twenty-fifth  of  July,  with  turnips,  and  in  October  a  good  sup- 
ply of  feed  would  be  furnished  for  the  farm  stock. 

In  the  cultivation  of  root  crops  more  attention  must  be 
paid  to  the  character  of  the  soil,  and  to  its  condition,  than 
for  the  cultivation  of  grain  crops,  and  hence  it  is  that  many 
farmers  who  have  tried  the  beet  and  ruta  baga  have  failed^ 
by  not  attending  to  the  proper  conditions ;  but  if  the  condi- 
tions are  adhered  to  the  crop  is  as  certain,  and  much  more 
profitable  than  grain  crops.  We  will  now  proceed  to  point 
out  the  requisite  conditions  for  root  culture,  with  the  theory 
of  the  action  upon  the  soil.  Attention  must  be  paid  to  the 
following  particulars. 

1.  llie  soil.  This  should  not  be  too  light  and  sandy,  nor 
too  stiff  and  clayey  ;  a  light  deep  loam  or  alluvial  soil  is  best 
adapted  to  this  crop.  If  the  soil  is  wet,  that  is,  if  water  is 
suffered  to  repose  upon  the  sub-soil,  the  roots  will  be  injured 
and  the  crop  fail.  The  soil  should  be  dry,  but  not  subject 
to  drought.  Depth  of  soil  is  a  necessary  requisite  for  beets 
and  ruta  bagas  in  order  that  the  roots  may  have  full  liberty 
to  penetrate  as  far  as  needful  for  their  perfection. 

2.  A  rich  soil  is  another  requisite  to  success.  This  is  de- 
sirable for  all  kinds  of  grain,  but  especially  for  root  culture  ; 
for  although  roots  do  not  draw  upon  soil,  like  grain  crops, 
still  there  must  be  abundant  food  present,  in  order  to  give 
them  that  quality  and  perfection  which  makes  them  profita- 
ble crops.  It  may  be  that  there  is  something  in  the  consti- 
tution or  vital  powers  of  these  plants,  which  renders  a  large 
quantity  of  nourishment  necessary  to  their  support.  They 
may  not  possess  the  power  of  collecting  food,  like  other 
plants ;  they  cannot  gather  up  the  nutriment  so  readily,  and 

24 


282  IMPROVEMENT   OF   THE    SOIL 

hence  must  be  fed  with  richer  food.  The  soil  must  hejinely 
pulverized,  and,  so  far  as  is  practicable,  freed  from  stones. 
This  is  necessary  in  order  that  the  roots  may  not  be  ob- 
structed ;  finally,  they  should  be  kept  free  of  weeds.  The 
ground  should  be  stirred  with  the  cultivator  and  hoe.  If 
sowed  in  rows,  as  they  should  be,  this  may  be  easily  attend- 
ed to  with  the  plough  and  cultivator,  without  the  necessity  of 
resorting  to  the  hoe  more  than  once  in  the  season. 

Theory  of  the  action  of  roots  upon  the  soil.  I.  They  di- 
vide it  better  than  most  crops  ;  2.  they  deepen  the  soil  by 
their  roots;  and  3.  return  to  the  soil  a  larger  amount  of  ma- 
nure than  other  crops. 

Three  acres  of  grass,  at  two  tons  per  acre,  will  give  less 
than  9,000  lbs.  to  the  cattle-yard,  while  one  acre  of  ruta  ba- 
ga  or  beets,  will  give  36,000  lbs.  or  more  than  four  times 
as  much  as  the  three  acres  of  grass  land.  It  would,  there- 
fore, be  economy  for  the  farmer  to  raise  roots  merely  for  ma- 
nure. But  the  one  acre  of  ruta  baga  or  beets  (600  bush- 
els) are  nearly  equal  to  three  acres  of  hay,  as  food  for  farm 
stock  ;  hence  the  modes  by  which  roots  improve  the  soil,  are 
dividing  and  deepening  it,  furnishing  a  larger  supply  of  food, 
which  enables  the  farmer  to  keep  a  larger  farm  stock,  by 
which  the  quantity  of  manures  are  increased.  Manure  is  the 
great  source  of  fertility.  In  proportion,  therefore,  as  root 
culture  is  made  a  part  of  a  rotation  system,  we  should  ex- 
pect the  soils  to  increase  in  fertility. 


CHAPTER  VII. 

IMPROVEMENT  OF  THE  SOIL  BY  MANURES  AND  TILLAGE. 

The  improvement  of  the  soil  by  manures  surpasses   all 
other  methods.     This  subject  is  one  that  comes  more  di- 


BY  MANURES.  283 

rectly  under  the  notice  of  tlie  farmer,  than  any  other  pertain- 
ing to  his  employment.  It  is  one  which  may  derive  the  most  aid 
from  science.  In  fact  it  is  the  most  important  branch  of 
Agricultural  Chemistry,  to  point  out  the  best  and  cheapest 
modes  of  preparing  manures  in  sufficient  quantities  ;  of  ap- 
plying them  to  different  soils,  and  for  different  crops  ;  and  to 
explain  the  theories  of  their  action  both  in  the  soil  and  in 
vegetation. 

Manures  contain  all  the  elements  of  fertility.  They  are 
composed  of  decaying  vegetable  and  animal  matter  (humus 
or  geine),  which  constitutes  the  largest  portion  of  them  ;  of 
a  small  quantity  of  silicates,  such  as  silicate  of  potash ;  and 
of  salts,  such  as  phosphates,  nitrates,  sulphates,  carbonates 
and  muriates. 

Manures  have  been  variously  classified.  A  very  ancient 
division  is  into  animal,  vegetable  and  mineral ;  thus  indicat- 
ing the  source  from  which  they  are  derived. 

The  classification  proposed  by  Dr.  Dana*  appears  to  be 
the  most  scientific  as  well  as  practical.  His  classes  depend 
upon  the  quantity  of  geinef  and  salts.  This  arrangement, 
with  some  modifications,  will  be  adopted  in  this  work. 

1.  Mixed  manures,  or  those  which  consist  of  salts  and 
geine. 

2.  Manures  which  consist  mostly  of  salts,  derived  from  ani- 
mal and  vegetable  bodies. 

•     3.  Manures  which  consist  mostly  of  geine. 

4.  Saline  manures,  or  those  which  are  composed  of  inor- 
ganic salts. 

The  points  most  worthy  of  attention,  both  in  a  scien- 
tific and  practical  view,  are  the  nature  and  composition  of  the 

*  Muck  Manual,  p.  124. 

t  The  term  geine  is  used  here  not  as  synonymous  with  huviic  acid, 
but  with  humus ;  and  wherever  it  is  used,  in  treating  of  this  subject, 
it  is  intended  to  include  the  organic  portions  of  manures,  or  the  de- 
caying organic  matter. 


284  IMPROVEMENT  OP  THE  SOIL 

different  substances  used  for  manure,  their  comparative  value, 
the  best  methods  of  preparing,  preserving  and  applying  them, 
and  the  theory  of  their  action  in  the  soil.  These  topics, 
therefore,  will  receive  particular  attention  in  the  following 
sections. 


Sect.  1.  Mixed  Manures,  or  those  wliicli  consist  of  Salts  and 
Gcine. 

This  class  includes  by  far  the  greatest  number  of  sub- 
stances which  are  employed  as  manures.  It  includes,  1.  the 
solid  excrements  of  animals,  such  as  those  of  the  cow,  horse, 
hog,  sheep  and  fowls,  night-soil  and  poudrette ;  2.  animal 
substances  which  contain  nitrogen,  such  as  flesh,  fish,  bones, 
hair,  wool  and  soot ;  3.  animal  and  vegetable  bodies,  which 
are  destitute  of  nitrogen,  as  oils,  fats  and  spent  lye  of  soap- 
boilers. 

I.  Solid  excrements  of  animals.  By  an  examination  of 
several  kinds  of  excrements,  and  their  known  effects,  we  can 
learn  the  reason  of  their  influence ;  and,  by  comparison,  as- 
certain what  elements  give  them  their  cojTiparative  value. 

1.  Cow  dung  is  taken,  by  Dana,  as  *'  the  type  of  manures," 

or  standard  of  value,  with  which  all  others  may  be  compared. 

The  following  is  Dana's  analysis  of  100  parts  of  fresh  fallen 

cow  dung. 

Water  83.60 

r  Hay  14.60 

Organic  matter^  -l  Bile,  and  resinous  and  biliary  matter         1.275 

[Albumen  .175 

r  Silica  .14 

Sulphate  of  potash  .05 

Geate  of  potash  .07 

.  Muriate  of  soda  .08 

]  Phosphate  of  lime  .23 

Sulphate  of  lime  .12 

Carbonate  of  lime  .12 

Loss  0.14 


Salts. 


100.000 


BY  MIXED  MANURES.  285 


Morin's  analysis  is  very  similar.     Thus  100  parts  consist  of 

Peculiar  extractive  matter  1.60 
Albumen  0.40 

Biliary  resin  1.80 


Water  70. 

Vegetable  fibre  24.08 

Green  resin  and  fat  acids    1.52 
Undecomposed  biliary  matt.  60 


lOO.Oi) 


Others  have  given  analyses  varying  somewhat  from  either  of 
the  above.  In  all  cases  there  is  from  70  to  85  per  cent,  of 
water,  which  of  course  is  of  no  more  value  than  any  other 
water.  By  Dana's  analysis  a  little  less  than  one-sixth 
part  consists  of  vegetable  matter  and  salts.  By  other  analy- 
ses, a  little  more  than  one-fourth  is  vegetable  matter.  A  large 
portion  of  the  vegetable  matter  is  hay,  bruised  and  deprived 
of  a  part  of  its  gum  and  albumen.  But  by  passing  through 
the  animal  organs,  the  chopped  hay  has  a  greater  tendency 
to  decay  than  common  hay.  The  living  power  has  exerted 
a  catalytic  force,  and  the  elements  are  disposed  to  separate ; 
hence,  nearly  the  whole  soon  becomes  humus  or  geine.  When 
subjected  to  ultimate  analysis,  100  parts  of  cow  dung  are 
composed  of  the  following  organic  elements. 

Nitrogen  .506  i  Hydrogen  .824 

Carbon  .204  I  Oxygen  4.818 

The  absolute  value  of  this  manure  will  not  depend  upon 
the  quantity  of  these  four  substances,  which  it  is  capable  of 
yielding  to  plants,  but  upon  the  quantity  of  geine,  ammoniacal 
and  other  salts.  The  relative  value  will  depend  upon  the 
proportion  of  nitrogen,  or  the  quantity  of  ammonia  which  it  is 
capable  of  forming.  All  manures  may  be  estimated  in  a 
similar  manner.  This  quantity  of  ammonia  may  be  deter- 
mined with  some  degree  of  accuracy  from  the  known  quan- 
tity of  nitrogen  ;  for  14  parts  of  nitrogen  and  3  of  hydrogen 
combine  to  form  17  of  ammonia.  From  these  data,  100  lbs. 
of  cow  dung  will  yield  0.614  or  about  five-eighths  of  a  pound 
of  ammonia.  This  is  generally  combined  with  carbonic  acid, 
and  would  make  about  2  lbs.  and  2  oz.  of  the  carbonate  of 
ammonia,  which  is  known  as  salts  of  hartshorn. 
24* 


286  IMPROVEMENT  OF  THE  SOIL 

The  salts  of  potash,  soda  and  lime,  are  much  less.  The 
whole,  including  the  salts  of  ammonia,  may  be  estimated  at 
2Jlbs.  in  100  of  manure. 

The  quantity  of  nitrogen  in  cow  dung  has  been  proved, 
by  experiment,  to  exceed  that  found  in  the  food  eaten. 
A  cow,  fed  on  24  lbs.  of  hay  and  12  lbs.  of  potatoes, 
yielded  daily  85.57  lbs.  of  dung,  or  14  J  lbs.  of  solid  ma- 
nure. This  contained  3.03  of  nitrogen,  while  the  hay,  etc. 
contained  only  1.67  parts ;  hence,  a  part  must  be  derived 
from  the  air. 

The  daily  droppings  of  one  cow  are  sufficient  for  one  half 
bushel  of  corn.  The  quantity  produced  per  year  is  sufficient 
to  fertilize  an  acre.  It  will  consist  of  the  following  sub- 
stances. 

Carbonate  of  lime  37  lbs. 

Common  salt  24    " 

Sulphate  of  potash  15   " 

Total  3r025   " 

Here  is  sufficient  lime  for  60  bushels  of  wheat,  and  the  straw 
grown  on  3  acres.  But  the  power  of  the  manure  to  form 
ammonia  and  nitrates,  constitutes  its  relative  value.  The 
same  is  true  of  all  other  manures. 

2.  Horse  manure.  Recent  horse  dung  is  highly  saturated 
with  water,  and  covered  with  mucus.  Its  character  and  nu- 
tritive qualities  vary  somewhat,  according  to  the  nature  of  the 
food.  Horses  fed  on  grain  yield,  of  course,  a  more  valuable 
article,  than  those  fed  upon  hay  alone.  According  to  the 
analysis  of  Dr.  C.  T.  Jackson,  100  grains  of  recent  manure 
consists  of 


Geine 

4400  lbs 

Carb.  ammonia 

550   " 

Phosphate  of  lime 

71    " 

Plaster 

37  " 

Water  71.40 

Veg.  and  animal  mattter  27.00 
Silica  .64 

Phosphate  of  lime  .08 


Carbonate  of  lime  .30 

Phosph.  of  magnesia  &sod;i  .58 

100.00 


It  will  be  seen  that  the  quantity  of  vegetable  and  animal  mat- 
ter is  considerably  larger  than  in  cow  dung.  It  is  as  14  to 
27,  or  nearly  double  ;  and  of  course  the  quantity  of  nitrogen 


BY  MIXED  MANURES.  287 

which  it  is  capable  of  yielding  is  nearly  double  that  of  cow 
dung  :  100  lbs.  of  fresh  manure  would  yield  about  3.24  lbs. 
of  carbonate  of  ammonia  and  about  .96  of  phosphates. 

3.  Sheep  dung  is  similar  to  horse  dung,  but  contains  a 
larger  quantity  of  vegetable  matter  in  a  soluble  state.  It  is 
also  richer  in  salts  ;  and  the  fact  that  it  tends,  like  the  dung 
of  fowls,  to  putresence,  shows  that  the  quantity  of  nitrogen 
which  it  is  capable  of  yielding,  is  greater  than  either  of  the 
preceding  substances. 

4.  Hog  manure.  Hog  manure  is  the  most  valuable  of  ma- 
nures. It  contains  still  larger  quantities  of  soluble  matter, 
and  is  capable  of  yielding  a  large  quantity  of  nitrogen  in  the 
form  of  ammonia.  We  have  not  seen  any  analysis  of  hog 
dung,  but  from  its  known  effects  it  ranks  next  in  value  to 

5.  Night  soil,  which  has  always  been  celebrated  as  the 
most  valuable  substance  used  for  manure.  The  reason  for 
its  powerful  effects  may  be  learned  from  its  composition : 
100  parts  of  pure  night  soil  contain 

Water  75.3  j   Pliosph.  of  lime  and  magnesia  .4 

Animal  and  veg.  matters    23.5  

Carb.,  mur.,  &  sulph.  of  soda  .8  100.0 

It  will  be  seen  that  the  quantity  of  nitrogen,  which  night  soil 
is  capable  of  yielding,  is  about  3J  per  cent.  The  quantity  of 
carbonate  of  ammonia,  which  may  be  formed  by  the  nitrogen, 
is  about  15  lbs.  in  100  of  night  soil ;  hence,  if  its  value  is  es- 
timated by  the  ammonia  which  it  is  capable  of  forming,  it  is 
more  than  seven  times  that  of  cow  dung.  Experiments  show, 
that  if  land  without  manure  yields  3  for  1  sown,  then  by  the 
addition  of  cow  dung,  it  will  yield  7  to  1  ;  of  horse  dung,  10 
to  1  ;  and  night  soil,  14  to  1. 

The  substances,  now  considered  are  generally  formed  to- 
gether, and  mingled  in  the  cattle  yard  and  hog  stye.  They 
constitute  the  great  sources  of  fertility  to  the  farm  ;  and  be- 
fore describing  the  other  substances,  which  come  under  this 


288  IMPROVEMENT  OF  THE  SOIL 

head,  it  is  important  to  inquire  after  the  best  modes  of  saving 
and  preparing  them. 

This  knowledge  may  be  obtained  from  the  nature  of  the 
changes  which  take  place  in  them,  in  passing  to  a  state  in 
which  they  can  be  absorbed  by  the  roots  of  plants. 

1.  If  these  substances  are  exposed  to  the  influence  of  rains, 
nearly  the  whole  of  the  soluble  geinc*  the  urine  and  soluble 
salts  will  be  dissolved  out,  and  washed  away  ;  hence,  they 
should  always  be  put  under  some  kind  of  covering,  such  as  a 
shed  or  barn  cellar,  which  will  prevent  this  waste.  The 
practice  of  throwing  manure  from  the  stables  into  the  open 
yard,t  is  as  wasteful,  as  it  would  be  for  the  manufacturer  of 
soap  or  potash,  to  leave  his  ashes  exposed  to  rains  for  a  long 
time  before  leaching  them.  This  evil  may  be  corrected  in 
part,  by  the  shape  of  the 

(1)  Cattle  yard,  which  should  descend  from  all  parts  to- 
wards the  centre;  and  by  covering  the  bottom  of  the  yard 
with  swamp  muck  or  peat  earth,  to  absorb  the  juices  which 
pass  through.  As  apart  of  the  manure  is  voided  in  the  yard, 
such  a  shape  is  needed  in  order  to  secure  it.  About  one 
third  of  the  manure  may  be  saved  by  these  means.     But, 

(2)  A  barn  cellar  is  the  preferable  mode  of  preventing 
this  waste,  because  it  is  more  convenient,  and  more  perfectly 
secures  the  desired  object.  This  should  be  of  the  same  shape 
as  the  cattle  yard,  and  lined  in  the  same  manner  with  muck. 
If  now  the  hogs  are  permitted  to  work  over  the  refuse  of  the 
stables,  and  the  night-soil,  a  task  which  they  will  perform 
with  admirable  skill,  provided  a  little  corn  is  occasionally 
added,  the  leaching  process  will  be  entirely  prevented,  and 
the  whole  will  be  thoroughly  mingled  together. 

*  The  term  soluble  geine,is  used  to  include  Iiumic,  crenlc  and  apo- 
crenic  acids,  and  their  soluble  salts. 

t  Some  recommend  the  practice  of  frequently  sprinkling  plaster 
over  the  manure  and  in  stables,  to  absorb  the  gaseous  ammonia,  which 
will  otherwise  be  lost. 


BY  MIXED  MANURES.  289 

2.  If  the  manure  is  suffered  to  remain  in  the  yard  or  cellar 
for  any  length  of  time,  it  should  be  covered  with  muck  or 
earth,  in  order  to  absorb  the  gaseous  bodies  which  will  be 
evolved. 

A  series  of  chemical  changes  now  commence.  The  whole 
grows  warm,  and  after  a  few  months  crumbles  down  to  a  uni- 
form mass,  and  becomes  short  muck  or  rotted  manure ;  con- 
taining a  larger  quantity  of  soluble  matter  (soluble  geine  and 
salts)  than  it  did  in  the  green  state.  This  process  was  for- 
merly called  fermentation,  but  now  it  includes  the  processes 
oi  fermentation,  putrefaction  and  decay.  The  changes  indi- 
cated by  these  terms,  all  agree  in  this  particular  ;  that  new 
compounds  are  formed,  either  by  a  different  arrangement  of 
the  elements  which  compose  any  one  compound  in  the  mass, 
or  by  the  agency  of  air  and  water,  whose  elements  combine 
with  the  ingredients  of  the  manures.  The  matter,  which  has 
passed  through  the  animal  organs,  is  much  more  easily  de- 
composed than  it  was  before,  and  a  series  of  chemical  trans- 
formations commence. 

(1)  When  bodies  which  contain  no  nitrogen  are  decom- 
posed, the  gaseous  products  have  no  odor  ;  as  when  sugar  is 
converted  into  alcohol  and  carbonic  acid,  and  in  most  cases 
of  fermenting  liquors,  the  process  is  c?i\]ed  fcnnentation. 

(2)  When  bodies  containing  nitrogen  suffer  decomposition, 
and  give  rise  to  gases  which  emit  a  disagreeable  smell,  the 
process  is  called  putrrf action.  But  these  changes  are  of  the 
same  kind,  although  the  latter  is  most  beneficial  to  the  far- 
mer, as  ammonia  is  generally  formed. 

(3)  When  any  body  decays  at  the  expense  of  the  oxygen 
of  the  air  by  a  kind  of  slow  combustion,  it  is  called  a  process 
of  decay  ("  eremacausis^^)  and  differs  from  fermentation  and 
putrefaction  in  the  circumstance,  that  oxygen  is  absorbed 
from  the  air  continually ;  while  in  fermentation,  if  a  small 
quantity  of  oxygen  is  admitted  to  the  body,  sufficient  to  com- 
mence the  process,  it  will  continue  without  further  aid  from 


290  IMPROVEMENT  OF  THE  SOIL 

the  air,  and  in  putrefaction  the  air  is  not  needed  at  all,  but 
the  process  is  often  promoted  by  excluding  oxygen  altogether. 

The  carbon,  oxygen,  hydrogen,  nitrogen  and  other  substan- 
ces of  which  manures  are  composed,  form  themselves  into 
several  new  compounds  which,  without  attem])ting  to  point 
out  all  the  changes  which  take  place,  finally  result  in  the  for- 
mation of  several  bodies  already  considered. 

These  substances  depend  upon  the  conditions  under  which 
the  changes  take  place.  If  the  changes  occur  in  the  earth, 
they  give  rise  to  fossil  coal.  If  they  take  place  near  the  sur- 
face of  the  ground,  or  in  the  open  air,  which  is  the  case  un- 
der consideration,  they  give  rise  to  the  substances  found  in 
vegetable  mould,  p.  215,  and  in  the  atmosphere. 

Theories  of  the  changes  which  take  place  in  fermenting 
dung-heaps^  in  the  process  of  decomposition. 

(1)  Carbonic  acid  in  large  quantities  is  formed.  This  re- 
sults either  from  the  direct  combination  of  the  oxygen  of  the  air 
and  of  water  with  the  carbon  of  the  plant,  or  from  the  union 
of  the  oxygen  of  the  air  with  the  hydrogen  of  the  plant  to 
form  water,  while  the  carbon  and  the  oxygen  of  the  vegeta- 
ble is  evolved  in  the  form  of  carbonic  acid.  By  this  process, 
a  large  portion  of  the  carbon  is  abstracted  in  a  gaseous  form, 
and  unless  alkalies  or  earths  are  present  to  absorb  it,  passes 
off  into  the  atmosphere. 

(2)  Water  is  formed  at  the  same  time  with  carbonic  acid. 
The  hydrogen  is  furnished  from  the  vegetable  matter,  and  the 
oxygen  from  the  air.  The  quantity  of  water  thus  annually 
formed  in  the  soil,  is  probably  greater  than  that  which  falls 
in  rain  on  the  same  surface.  In  dung-heaps,  the  quantity  of 
water  formed  is  far  greater  than  in  the  soil.  In  these  pro- 
ducts there  is  a  genuine  process  of  decay. 

(3)  As  all  parts  of  the  heaps  are  not  exposed  alike  to  the 
action  of  the  air,  the  hydrogen  and  the  carbon  combine  and 
form  carbureted  hydrogen.  The  hydrogen  is  fiirnished  either 
from  the  vegetable  itself,  or  from  the  water  which  is  known 


BY  MIXED  MANURES.  291 

to  be  decomposed  in  the  process.     This  also   escapes   into 
the  air. 

(4)  Sulphur  and  phosphorus  are  always  constituents  of 
manures,  and  combine  with  the  hydrogen  and  form  sulphuret- 
ed  and  phosphoreted  hydrogen  ;  two  gaseous  bodies  of  very 
offensive  odors,  which  escape  in  part  into  the  air. 

(5)  The  substances  which  contain  nitrogen  yield  that  ele- 
ment to  hydrogen,  and  form  ammonia.  A  part  of  this  sub- 
stance is  absorbed  by  water  and  the  vegetable  matter,  and  a 
part  is  thrown  off  into  the  atmosphere  ;  the  remainder,  which 
constitutes  probably  the  largest  portion,  combines  with  car- 
bonic acid,  forming  carbonate  of  ammonia,  and  with  other 
acids,  as  the  muriatic  and  nitric,  which  are  formed  during 
the  process. 

The  above,  with  the  exception  of  water,  are  the  gaseous 
bodies  given  off  in  the  process,  and  as  the  most  valuable  part 
of  the  manure  is  liable  to  be  dissipated  in  this  way,  v/e  have 
the  best  reason  for  covering  the  fermenting  heap  with  a  thick 
coating  of  earth  or  peaty  matter. 

(6)  Nitric  acid  is  usually  formed  in  this  process.  Some 
have  supposed  that  it  results  from  the  transformation  of  am- 
monia ;  others  suppose  that  it  may  obtain  its  nitrogen  direct- 
ly from  the  plant,  or  from  the  atmosphere.  The  acid  being 
formed,  combines  with  the  potash  and  forms  nitre  or  salt- 
petre ;  and  with  other  bases  which  may  be  present,  such  as 
soda,  lime  and  ammonia. 

(7)  Sulphuric  and  hydrochloric  acids  are  also  formed ;  the 
latter  acid  deriving  its  chlorine  from  the  salt  which  exists  in 
animal  excrements.  It  is  probable  that  other  acids  are  formed. 
All  of  them,  however,  are  combined  with  bases  in  the  form 
of  salts.  It  is  rare  that  any  acid,  excepting  the  carbonic,  ex- 
ists in  a  free  state. 

(8)  The  solid  matters  which  remain,  are  found  to  consist 
in  part  of  humic  acid,  humin,  extract  of  humus,  crenic  and 
apocrenic  acids.     The  acids   are  combined  in  some  cases 


292  IMPROVEMENT  OF  THE  SOIL 

with  bases,  and  the  whole  taken  together  has  been  called  geine 
and  humus.  But' when  the  fermenting  heap  is  exposed  to  the 
rains,  the  salts  and  the  vegetable  matters  are  dissolved  by  the 
water,  and  pass  down  into  the  soil  or  run  to  waste  ;  hence, 
the  reason  for  the  direction  above  given,  to  place  under  the 
heap  a  thick  bed  of  earth  or  swamp-muck,  to  absorb  these 
liquid  matters. 

When  these  changes  have  proceeded  awhile,  the  whole  mass 
is  converted  into  an  effectual  manure,  into  geine  and  salts,  fit- 
ted for  any  soil  or  crop.  If  the  heap  contain  a  large  quan- 
tity of  animal  matter  ,  the  tendency  to  putrefaction  is  much 
increased,  a  much  larger  quantity  of  ammonia  is  formed,  and 
also  a  larger  quantity  o(  nitrates. 

3.  If  the  manures  are  carried,  in  their  green  state,  direct- 
ly upon  the  field,  as  a  top  dressing,  the  air  of  course,  and 
not  the  crop,  receives  the  larger  portion  of  their  valuable 
products.  But  if  they  are  spread,  and  turned  into  the  soil, 
the  changes  which  we  have  described  take  place  much  more 
slowly,  a  circumstance  which,  on  many  accounts,  is  highly 
favorable  to  vegetation.  The  plant  requires  a  constant  and 
regular  supply  of  nutriment,  and  this  process  supplies  it. 
The  heat,  which  always  attends  their  decompositions,  acts 
with  great  power,  and  with  the  best  effect,  especially  in  cold 
wet  soils.  The  gaseous  matters  are  directly  absorbed  by 
the  loam,  and  more  perfectly  retained  than  they  can  be  in 
the  heap.  Still  it  may  be  doubted,  whether  the  manure,  from 
its  diffusion  through  the  soil,  is  as  favorably  situated  for  those 
chemical  changes,  which  must  take  place,  before  it  can  nour- 
ish plants.  It  may  well  be  doubted  whether  so  large  a  quan- 
tity of  soluble  geine  and  salts  will  be  furnished  in  this  way, 
as  when  placed  under  fitting  circumstances  in  heaps,  and 
whether  more  vegetable  matter  will  not  be  dissipated  in  the 
air. 

If,  however,  soils  are  wet  and  cold,  manures  should  be  ap- 
plied in  the  green  state,  rather  than  permitted  to  ferment  in 


BY  MIXED  MANURES. 


293 


the  yard.  It  may  be  remarked,  generally,  that  in  all  cases 
where  manures  are  applied  without  forming  them  into  com- 
post heaps,  they  should  be  applied  in  the  green  state,  but  when 
composted  with  vegetable  matter,  it  is  far  preferable  to  allow 
them  to  pass  through  the  fermenting  processes. 

6.  Poudrette  is  night  soil  mixed  with  ground  peat  and 
plaster,  and  dried  so  as  to  be  rendered  inodorous  and  porta- 
ble. If  the  sulphate  of  lime  and  peat  are  added  before  it  is 
dried,  the  ammonia  will  be  converted  into  a  sulphate,  or  ab- 
sorbed by  the  peat  and  retained.  The  value  of  good  pou- 
drette depends  upon  the  quantity  of  ammonia  and  geine.  It 
has  been  valued  in  comparison  with  cow  dung  as  14  to  I.* 

7.  Chiano  is  a  very  valuable  manure.  It  is  the  excrements 
of  birds,  and  is  found  in  the  greatest  abundance  on  the  islands 
of  the  Southern  Ocean,  where  it  forms  beds  from  eighty  to 
ninety  feet  in  thickness.  It  is  composed,  according  to  Voel- 
ckel,  of 


Urate  of  ammonia  .9 

Oxalate  of  ammonia  10.6 

Oxalate  of  lime  7.0 

Phosphate  of  ammonia  6.0 

Phos,  of  ammonia  and  mag.  2.6 

Sulphate  of  potash  5.5 


Sulphate  of  soda  3.8- 

Muriate  of  ammonia  4.2 

Phosphate  of  lime  14.3 

Clay  and  sand  4.7 

Undetermined  organ,  sub.  32.3 
of  which  12  per  cent,  is  soluble. 


This  substance  is  said  to  render  fertile  the  soils  of  Peru, 
which  do  not  contain  a  particle  of  organic  matter.  It  will 
be  seen  from  its  composition  that  it  contains  all  the  elements 
of  fertility,  a  large  quantity  of  salts,  and  12  per  cent,  of  sol- 

*  There  is  yet  another  form  of  poudrette,  which  though  much  used 
in  France,  has  not  been  introduced  here.  It  is  almost  one-half  ani- 
mal matter,  and  it  is  formed  without  any  offensive  evolution  of  gas, 
by  boiling  the  offal  of  the  slaughter-house,  by  steam,  into  a  thick 
soup,  and  then  mixing  the  whole  into  a  stiff  paste,  with  sifted  coal 
ashes,  and  drying.  If  putrefaction  should  have  begun,  the  addition 
of  ashes,  sweetens  the  whole,  and  the  prepared  "  animalized  coal,"  as 
it  is  termed,  or  poudrette,  is  as  sweet  to  the  nose,  as  garden  mould. 
It  is  transported  in  barrels  from  Paris  to  the  interior,  and  is  a  capital 
manure. — Dana's  Muck  Manual. 

25 


294  IMPROVEMENT  OF  THE  SOIL 

uhle  organic  matter.  Liebig  appeals  to  this  example  to  prove 
that  plants  will  grow  without  humus  ! 

8.  Pigeon  dung  and  that  from  domestic  fowls  is  similar 
to  guano.  The  former  has  been  proved  by  experiment  to 
be  f  stronger  than  horse  dung.  The  manure  of  fowls  has 
been  applied  with  the  best  effects  to  peach  trees,  vines  and 
other  plants,  which  after  a  few  years  present  the  most  luxuri- 
ant and  healthy  appearance.  It  may  be  applied  by  mixing 
one  part  of  manure  with  8  or  10  of  water,  and  put  around 
the  roots. 

II.  Animal  bodies,  such  as  flesh,  skin,  gristle,  sinews 
and  bones,  form  by  decomposition  most  powerful  manures. 
They  produce  much  larger  quantities  of  ammonia  than  fer- 
menting dung  heaps,  and  are  much  richer  in  salts,  contain- 
ing in  fact  all  the  substances  which  are  necessary  to  sup- 
port the  vegetable  organs.  The  following  table  shows  the 
composition  of  animal  bodies. 

{Sulphate  and  phosphate  of  lime, 
Phosphates  of  soda,  magnesia  and  ammonia, 
Sulphate  and  muriate  of  potash  and  soda. 
Carbonates  of  potash,  soda,  lime  and  magnesia. 

V       ♦  Ki      C  Benzoate,  ^ 

vegeiaDie    i  Acetate,    \  Of  potash,  soda,  lime. 
^^^^^-        ^Oxalate,    ^ 

Animal  C  Urate  of  ammonia. 
Salts.    \  Lactate  of  ammonia.    • 

Oxides  of  iron,  manganese  and  silica. 

Animals  and  vegetables  contain  several  substances,  which 
appear  to  be  identical.  Gluten,  vegetable  fibrin,  albumen 
and  legumin,  are  vegetable  principles,  and  the  correspond- 
ing substances  in  animals  are  fibrin,  albumen  and  casein. 
The  last  two  are  identical  in  composition  with  vegetable  al- 
bumen and  legumin.  These  principles  are  combined  with 
alkalies,  earths,  sulphur  and  phosphoric  acid.  When  de- 
prived of  their  inorganic  portions,  they  have  been  referred  to 
a  single  organic  principle,  called  protein,  which  is  thus  con- 
stituted. 


BY  MIXED  MANURES.  295 

Oxygen  21.2.88  I  Carbon  55.742 

Hydrogen  6.827  |  Nitrogen  16.143 

IM. 
or  in  symbols  C'^^H^SN^O^'*.  It  appears  now  to  be  well  estab- 
lished   that  this  substance   is  the  basis  of  animal  bodies. 
Fibrin  or  flesh,  and  albumen  or  the  white  of  eggs,  are  com- 
posed of  protein  and  sulphur.  " 

Horny  matter  is  of  two  kinds,  soft  and  compact.  The 
soft  variety  includes  the  cutiele  of  the  skin,  and  the  lining 
membrane  of  the  internal  passages  and  sacs. 

The  eompact  variety  includes  horns,  hoofs,  nails,  claws, 
scales,  feathers,  hair  and  wool.  These  substances  all  con- 
tain sulphur,  lime,  magnesia,  and  from  ^  to  2  per  cent,  of 
bone  earth.* 

1.  Horns  and  hoofs.  The  shavings  and  piths  of  horns 
and  hoofs  of  neat-cattle  make  a  very  powerful  manure.  About 
0.3  per  cent,  is  phosphate  of  lime  and  earthy  matter  ;  the  re- 
maining substances  are,  in  100  parts. 

Carbon  51.540  i   Nitrogen  17.284 

Hydrogen  6.7D9  \  Oxygen  and  sulphur       24.397 

The  horns  and  piths  may  be  cut  with  an  axe  or  ground  in  a 
bone-mill,  then  mixed  with  green  manure,  a  bushel  to  a  load, 
spread  upon  the  field,  and  buried  with  the  plough.  The  fer- 
mentation of  the  dung  promotes  the  decay  of  the  animal  mat- 
ter, and  large  quantities  of  ammonia  will  be  evolved. 

2.  Nails  and  claivs  are  composed  of 

Carbon  51.019  I   Nitrogen  16.901 

Hydrogen  6. 824  |  Oxygen  and  sulphur        24.608 

These  of  course  will  yield  a  large  quantity  of  ammonia,  and 
therefore  they  will  constitute  a  powerful  manure. 

3.  Hair  is  composed  of 

Carbon  50.652  |  Nitrogen  17.936 

Hydrogen  6.769  I   Oxygen  and  sulphur       24.643 

.  (Scherer.) 

*  Dana. 


Carbon 

50.653 

Hydrogen 

7.02!) 

Nitrogen 

17.710 

296  IMPROVEMENT  OF  THE  SOIL 

4.  Wool  contains,  in  100  parts, 

Oxygen  and  sulphur        24.608 

100.000 

5.  Feathers  are  composed,  in  100  parts,  of 

Carbon  52.427  I   Nitrogen  17.893 

Hydrogen  7.213  |  Oxygen  22.467 

Wool,  woollen  rags,  and  the  refuse  from  woollen  manufactories, 
hair  and  feathers,  contain  an  oil  in  addition  to  their  protein, 
which  increases  their  value,  and  renders  them  excellent  ma- 
nures. The  washings  from  the  wool  annually  consumed  in 
France,  would  yield  sufficient  manure  for  370,000  acres  of 
land.     This  wool-sweat  is  an  excellent  manure. 

G.  Glue,  jelly,  etc.  is  derived  from  cartilage,  skin,  bone 
and  tendon,  by  boiling  them  in  water  ;  but  it  is  not  found  in 
healthy  animals.     It  constitutes  a  powerful  manure. 

7.  Bones  are  composed  of  animal   matter,  phosphate  of 

lime  and  of  magnesia,  and  carbonate  of  lime:  100  parts  of 

the  bones  of  the  ox,  as  analyzed  by  Davy,  yielded,  of 

Decomposable  anini.  matter  .51   j   Carbonate  of  lime  10. 

Phosphate  of  lime  37.       '  Phosphate  of  magnesia         1.3 

The  value  of  bones  depends  upon  their  power  of  producing 
ammonia  and  salts.  For  the  former  purpose,  they  are  at 
least  8  or  10  times  as  valuable  as  cow  dung,  and  the  quantity 
of  salts  is  66  times  that  contained  in  an  equal  quantity  of  that 
substance.  They  constitute,  then,  a  most  concentrated  ani- 
mal manure,  and  have  been  long  used  by  the  most  intelligent 
farmers  for  improving  their  soils.  For  this  purpose  they  are 
crushed  in  a  mill,  made  for  the  purpose,  and  constitute 
Bone  dust.  The  value  of  this  manure  may  be  estimated 
by  the  quantity  which  is  imported  into  England,  amounting 
animally  to  800,000  dollars  worth.  It  is  estimated  that  this 
adds  to  the  agricultural  products  more  than  16  million 
bushels  of  grain..  Bone  dust  is  now  used  in  this  country  to  a 
considerable  extent.  One  bushel  to  a  load  of  yard  manure, 
increases  its  value,  as  determined  by  experiment,  one  half. 


BY  MIXED  MANURES. 


297 


Vegetable  matter  30.70 

Extract,  matter  &  nitrog.  20.00 
Carb.  of  lime  and  traces 

of  magnesia  14.66 

Acetate  of  lime  5.65 

Sulphate  of  lime  5.00 

Phosph.  of  lime  &  of  iron  1.50 


Bone  dust  not  only  acts  with  great  power,  but  its  effects 
continue  a  long  time ;  and,  as  it  contains  salts  of  lime,  it  is 
particularly  useful  to  the  soils  of  New  England. 

8.  Sootj  in  its  composition,  is  allied  to  animal  solids,  and 
may  be  described  in  thi^  connection.  It  is  a  very  valuable 
manure,  as  appears  from  its  composition :  100  parts  of  soot 
contain,  of 

Acetate  of  potash  4.10 

Muriate  of  potash  .36 

Acetate  of  ammonia  .20 

Acetate  of  magnesia  .53 

Silex  .95 

Carbon  3.85 

Water  12.50 
300.00 

If  the  value  be  determined  by  the  quantity  of  salts  and  of  nitro- 
gen, in  equal  weights  of  soot  and  cow  dung,  the  salts  are  as 
20  in  the  former  to  1  in  the  latter,  and  the  ammonia  as  40  to  1. 
The  application  of  soot-water  (6  quarts  of  soot  to  a  hogshead  of 
water)  to  green-house  plants,  has  been  attended  with  the  best 
effects. 

So  valuable  a  substance  ought  to  be  saved  with  the  utmost 
care,  and  either  applied  directly  to  the  soil  or  to  compost 
heaps.  The  latter  use  of  soot  is  the  most  profitable,  because 
it  is  capable  of  decomposing  a  large  quantity  of  vegetable 
matter,  as  peat  or  swamp  muck. 

III.  Animal  and  vegetable  substances  destitute  of  nitrogen. 
The  only  substances  belonging  to  this  class  are  oils  and  fats. 
In  order  to  understand  the  action  of  these  bodies  as  manures, 
it  will  be  necessary  to  ascertain  their  constitution.  Fatty  bodies 
are  acids  combined  with  a  peculiar  base  called  ^Zycerme,  which 
is  similar  to  stearine  and  margarine  or  fats,  and  to  oleine  or  oils. 
The  acids  are  stearic,  margaric  and  oleic  acids. 

When  oils  and  fats  are  exposed  to  the  air,  they  yield  great 

quantities  of  carbonic  acid,  and  become  converted  into  the 

above  acids.     The  carbonic  acid  acts  upon  the  silicates,  and 

the  organic  acids  act  upon  the  alkalies  in  the  soil,  and  form 

25* 


298  IMPROVEMENT  OF  THE  SOIL 

soaps,  which,  as  salts,  produce  a  most  powerful  effect  in  the 
processes  of  vegetation. 

1.  Soap-boilers^  spent  lye.  In  the  process  of  soap-making, 
the  alkali  combines  with  the  acid  of  stearine,  margarine  and 
oleine,  forming  stearates,  margarates  and  oleates  or  soaps, 
while  the  glycerine  remains  in  solution  with  the  salts. 

This  latter  substance  is  somewhat  similar  to  geine,  and  is 

thus  constituted. 

Carbon  40.07  I  Hydrogen  8.92 

Oxygen  51.00 

The  oxygen,  hydrogen  and  carbon  exist  in  such  proportions 
as  to  form  water,  carbon  and  carbureted  hydrogen.  It  may 
yield  to  plants  the  same  elements  as  humic  acid.  As  about 
8  per  cent,  of  oils  and  fats  is  glycerine,  it  will  readily  be  per- 
ceived, that  the  large  quantity  of  this  substance  in  spent  lye, 
must  render  it  a  very  valuable  manure. 

But  this  is  not  the  only  substance  which  gives  to  it  its 
value.  There  are  also  various  salts  ;  the  kind  depending 
upon  the  alkali  used  to  form  the  soap. 

1.  If  potash  is  used  (as  it  always  is  to  form  soft  soaps), 

every  100  lbs.  of  soft  soap  requires  about  8  bushels  of  ashes, 

and  the  spent  lye  contains,  of 

Sulphate  of  potash  6.5  lbs.  I   Silicate  of  potash  1.8  lbs. 

Muriate  of  potash  0.3  "     | 

and  a  small  quantity  of  potash  in  a  free  state.  This  adds 
greatly  to  the  value  of  this  article  as  a  manure. 

2.  If  now  common  salt  is  added  to  make  the  soap  grain,  or 
to  convert  the  soft  to  hard  soap,  the  salt  is  decomposed,  the 
soda  takes  the  place  of  the  potash,  and  forms  soda  soap,  while 
thechlorine  combines  with  the  potassium,  forming  the  chlo- 
ride of  potassium  (muriate  of  potash),  which  is  added  to  the 
spent  lye.  The  quantity  will  depend  upon  the  quantity  of 
salt*  used. 

*  In  a  boil  of  2,000  lbs.  of  soap,  about  7  bushels  of  salt  are  usually 
added. 


BY  ORGANIC  SALTS.  299 

3.  If  the  alkali  is  barilla  or  white  ash,  then  the  spent  lye 
will  contain,  in  addition  to  its  glycerine,  salts  of  soda;  but  as 
less  common  salt  is  added,  in  this  case/ the  quantity  of  sul- 
phate and  muriate  of  soda  will  be  less  than  the  corresponding 
salts  of  potash.  Ordinarily  the  spent  lye  of  hard  soap  contains, 
per  gallon,  of 

Sulphate  of  soda  6|  oz.  i   Glycerine  Alb 

Muriate  of  soda        .  ^Ib.   | 

"While  that  from  hard  soap  contains,  per  gallon,  of 

Glycerine  ^  lb.  I  Sulphate  of  potash  U  lbs. 

Muriate  of  potash  (chloride  Silicate  of  potash  2A  oz 

of  potassium)  ^5  " 

It  becomes  an  important  question,  whether  so  valuable  a  ma- 
nure can  be  imitated  by  artificial  methods.  As  soluble  geine 
is  similar  to  glycerine,  the  elements  of  spent  lye  from  soda 
soap  may  be  formed  from  swamp  muck,  ashes  and  common 
salt.  Take  100  lbs.  of  peat,  1  bushel  of  salt,  2  bushels  of 
ashes  and  200  gallons  of  water.  Mix  the  peat  and  ashes ; 
moisten  with  water  and  add  it  to  the  salt  in  solution  ;  stir  it 
occasionally  for  a  week,  and  it  will  be  fit  for  use.* 

Sect.  2.  Manure,  consisting  of  Salts  derived  from  Animal 
Bodies. 

This  class  of  manures  includes  the  liquid  evacuations  of 
animals,  which  are  salts  dissolved  in  water.  These  salts  are 
different  from  those  which  will  be  described  under  the  head 
of  mineral  or  saline  manures,  because  they  are  formed  of  an 
animal  acid;  that  is,of  an  acid  which  is  produced  in  the  ani- 
mal organs.  This  acid  is  found  in  urine,  and  is  called  uric 
acid.     It  is  composed  of 

Carbon  36.11   i  Oxygen  28  19 

Hydrogen  2.34  |  Nitrogen  33;36 

The  quantity  of  nitrogen  renders  it  a  powerful    manure,   as 
it  becomes  the  food  of  plants.     This  acid  appears  to  be'de- 

*  Dana. 


300  IMPROVEMENT  OF  THE  SOIL 

rived  from  an  animal  principle  called  urea;  which  may  be 
obtained  from  urine  in  transparent,  colorless  crystals,  very 
soluble  in  water,  in  which  it  suffers  no  change;  but  when 
mixed  as  in  urine,  it  is  converted  into  carbonate  of  ammonia. 
Alkalies  produce  the  same  effect. 
Urea  is  composed  of 

Carbon  19.99  I  Hydrogen  6.66 

Oxygen  26.66  |  Nitrogen  46.66 

The  oxygen,  carbon,  hydrogen  and  nitrogen  are  in  such  pro- 
portions, that  they  are  converted  ivholly  into  carbonic  acid 
and  ammonia  ;  hence,  the  quantity  of  urea  in  urine,  is  equal 
to  its  weight  of  carbonate  of  ammonia.  The  urea  and  uric 
acid,  render  the  liquid  excretions  of  animals  equally  valuable 
with  the  solid  evacuations ;  and  much  more  valuable,  when 
vegetable  matters  are  employed  to  absorb  the  gaseous  products. 
1.  Urine  of  the  cow.  The  liquid  evacuations  of  the  cow 
are  composed  of 


Water  65 

Urea  5 

Phosphate  of  lime  5 


Sal  amm.  and  mur.  of  potash     15 
Sulphate  of  potash  6 

Carbonate  of  potash  and  amm.    4 

~Ioo 


It  will  be  seen,  that  the  quantity  of  ammonia  in  the  urea, 
as  compared  with  cow-dung,  is  as  5  to  2  ;  and  in  the  other 
ammoniacal  salts  as  15  to  2,  or  about  4  times  the  quantity  of 
the  salts  of  ammonia  in  the  liquid,  that  there  is  in  the  solid 
evacuations. 

:*»'100dbs.  of  this  urine  yield  35  lbs.  of  the  most  power- 
ful salts  ;  hence,  the  importance  of  saving  the  urine  by  in- 
troducing into  the  yard  or  barn  cellar  substances,  as  peat, 
which  will  prevent  it  from  being  washed  away.  If  it  is  true, 
as  has  been  shown  by  experiment,  that  a  cord  of  loam  satu- 
rated with  urine  is  equal  to  a  cord  of  the  best  rotted  manure, 
and  if  one  cow  would  furnish  sufficient  annually  to  manure  an 
acre  and  one  half  of  land,  while  the  solid  evacuations  will  not 
fertilize  more  than  one  acre,  it  must  be  evident  to  every  far- 


BY  ORGANIC  SALTS.  301 

mer,  that  at  least  one  half  of  his  manure  is  wasted,  if  exposed 
to  the  influence  of  rains,  and  the  ordinary  action  of  the  at- 
mosphere. 

2.  Urine  uf  the  horse.  The  urine  of  the  horse,  and  some- 
times of  other  herbiferous  animals,  contains  hippuric  acid, 
which  takes  the  place  of  the  uric  acid.  The  result,  however, 
in  vegetation  is  nearly  the  same,  as  the  acid  in  both  cases 
gives  rise  to  ammonia  by  decomposition.  The  value  of 
horse-urine  will  appear  from  its  composition.  100  parts 
contain 


Water  G4.0 

Urea  .7 

Carbonate  of  soda  .9 


Carbonate  of  lime  1.1 

Hippurate  of  soda  2.4 

Muriate  of  potash  .9 

iocToo 


From  its  composition,  it  is  at  least  equal  in  value  to  cow-dung. 
3.  Human  urine  is  equally  valuable  with  either  of  the  pre- 
ceding.    It  is  composed,  in  1000  parts,  of 


Sal  ammoniac  .459 

Sulphate  of  potash  2.112 

Muriate  of  potash  3.674 

Common  salt  5.06'J 

Phosphate  of  soda  4.267 


Phosphate  of  lime  .209 

Acetate  of  soda  2.770 

Urate  of  ammonia  .298 

Urea  with  coloring  matter  23.640 
Water  S67.511 


The  quantity  of  salts  in  1090  lbs.  of  this  urine  is  upwards 
of  42  lbs.  The  salts  of  ammonia  makes  it  about  equal  in 
value  to  cow-dung,  pound  for  pound ;  but  as  the  other  salts 
are  more  than  double,  1000  lbs.  of  human  urine  is  worth 
nearly  2000  lbs.  of  the  best  cow-dung. 

If  now  we  compare  the  quantity  of  salts  in  the  solid,  with 
these  in  the  liquid  evacuations,  we  shall  find  that  human, 
horse  and  cow  dung,  contain  upon  an  average,  1  per  cent., 
while  human  urine  contains  4.24  per  cent.,  that  from  the 
horse  6,  and  that  from  the  cow  35  per  cent. 

There  is  no  substance,  however,  which  varies  more  in  com- 
position than  urine.  Its  composition  depends  upon  the  kind 
of  food,*  but  it  is  always  a  most  valuable  manure.   No  farmer 

*    "  White  turnips  give  a  weaker  liquor  than  Swedish.     Green 


302  IMPROVEMENT  OF  THE  SOIL 

should  permit  it  to  run  to  waste,  but  should  so  prepare  his 
cattle-yard  by  loam  or  swamp-muck,  and  by  plaster,  as  to 
save  these  invaluable  products  of  his  stables,  and  of  his  own 
dwelling. 

As  the  urine  is  generally  mixed  with  the  solid  excrements 
in  the  barn-cellar  or  cattle-yard,  it  increases  the  value  of  this 
manure,  it  promotes  its  decay,  and  adds  its  own  salts ;  but 
if  the  whole  is  exposed  to  the  influence  of  atmospheric  agents, 
it  facilitates  their  action,  and  aids  in  depreciating  its  value; 
hence,  it  is  generally  wholly  lost  to  the  farm.  Farmers  ought 
generally  to  know  this,  and  to  be  apprized  of  the  fact,  that 
one  half  at  least  of  their  manure  is  wasted.  The  prepara- 
tion of  liquid  manures  will  be  further  noticed  under  com- 
posts. 

Sect.  3.  Manures  composed  mostly  of  Geine. 

The  refuse  of  the  stables  and  of  the  farmer's  dwelling,  are 
the  general  sources  of  manure.  But  there  are  certain  artifi- 
cial preparations,  which  are  equally  efficacious,  and  which 
most  farmers  may  employ  to  increase  the  fertility  of  their 
soils. 

These  sources  are  decaying  vegetable  matters,  formed  in 
various  ways,  into  composts.  The  vegetable  substances  em- 
ployed for  these  purposes,  originate  from  two  classes  of  plants, 
sea-weeds  and  land  plants;  and  the  manures  which  they 
form,  differ  in  several  important  particulars,  but  agree  in 
yielding  all  the  elements  of  fertility. 

In  order  to  exhibit  the  facts  and  principles,  connected  with 
this  species  of  manures  in  a  practical  light,  it  will  be  neces- 
sary to  examine  the  composition  of  the  substances  employed 

grass  is  still  worse.  Distiller's  grains  are  said  to  be  better  than  either 
of  these.  Doubtless,  the  liquids  of  fattening  kine  is  richer  in  ammo- 
nia during  this  period,  for  it  contains  a  partof  the  nitrogen  not  carried 
away  in  the  milk." — Dana. 


i 


BY  MANURES  FROM  SEA-WEED.  303 

for  this  purpose,  and  the  changes  which  are  wrought  upon 
them,  in  their  conversion  into  vegetable  food. 

I.  Sea-iceed.  Sea  weeds  form  a  kind  of  manure  which  is 
much  used  along  the  sea  board.  The  manure  is  formed  from 
several  species  of  plants,  which  are  washed  upon  the  shore  by 
the  waves  and  either  carted  directly  upon  the  soil  or  used  for 
litter  and  composted  with  other  substances.  The  following 
are  the  principal  varieties. 

1.  Ribbon  loced,  or  narrow-leaved  kelp,  when  green,  is 
nearly  four-fifths  water.  When  dry,  400  grains,  burned  to 
ashes,  yielded,  of 


Carbonate  of  soda  (not  weighed) 
Phosphate  of  lime  "^    3.3 

Carbonate  of  hme  2.U 


Si  lex  0.2 

Magnesia  3,5 


*'  The  vegetable  matter  of  kelp  is  very  gelatinous,  and  melts 
down  during  fermentation  into  a  semi-liquid  mass."  The 
Scotch  farmers  make  great  use  of  this  substance,  and  prefer 
laying  it  directly  on  to  the  soil,  in  its  green  state. 

2.  GwMkg.t££3i  moss  contains  a  gelatinous  matter,  similar  to 
animal  gelatine.  It  is  used  for  food,  and  makes  a  delicate 
blanc-mange.      <  >     ^  ^.    ^ 

3.  Rock  ?veed  is  highly*  gelatinous  in  its  nature  and  very 
valuable  as  a  manure. 

4.  Eel  grass  consists  mostly  of  water  and  is  much  less 
valuable. 

5.  Sea  coral  is  often  thrown  up  with  sea  weeds,  and  adds 
greatly  to  their  value.  It  is  composed  of  the  following  sub- 
stances :   100  parts  contain,  of 

Animal  matter  14  I  Phosphate  of  lime  1 

Carbonate  of  lime  d,5  |  — rrrx 

The  quantity  of  salts  contained  in  sea  weeds  renders  them  a 
very  valuable  manure. 

Preparation  and  application  of  sea  iveeds.  If  sea  weed  is 
to  be  transported  to  some  distance,  it  should  be  dried,  to  evapo- 
rate the  water.     It  may  then  be  spread  directly  upon  the 


304  IMPROVEMENT  OF  THE  SOIL 

soil  and  ploughed  in,  or  formed  into  compost  with  fish,  or  the 
refuse  of  the  cattle  yard.  In  either  case  it  is  an  active  ma- 
nure ;  but  its  effects  are  not  lasting,  probably  owing  to  the 
ease  with  which  it  is  decomposed  and  either  dissipated  or  ab- 
sorbed by  the  roots  of  plants.  It  may  be  used  for  litter,  to 
absorb  the  liquid  and  gaseous  products  of  the  stables,  with 
the  best  results.  Its  value  has  been  fully  tested  by  many 
farmers  who  reside  in  the  vicinity  of  the  sea. 

II.  Peat,  sivamp  muck  and  pond  mud.  These  sub- 
stances are  very  abundant  in  the  eastern  part  of  Massachu- 
setts. Almost  every  farm  throughout  the  country  contains 
either  peat,  muck  or  mud  in  sufficient  quantity  for  farming 
purposes. 

1.  Peat  is  derived  from  the  decayed  roots  of  sphagnous 
mosses,  ferns,  stalks  of  swamp-plants  and  decaying  leaves ; 
the  peat  moss  constitutes  the  principal  mass.  There  is  also 
a  small  quantity  of  mineral  matter,  such  as  silex,  clay,  lime 
and  magnesia,  either  mixed  with  it  or  combined  with  vege- 
table acids.  Some  varieties  contain  sulphate  of  lime  (gyp- 
sum), oxide  of  iron  and  of  manganese.  The  value  of  peat  as 
a  manure  may  be  seen  from  its  composition.  The  mean  of 
20  analyses  of  the  peats  of  Rhode  Island,  by  Dr.  Jackson, 
gave  the  following  results. 


Water          from  10  to  25  pr  ct. 

Iron  and  alumina  1.34 percent 

Ashes,  when  burned,    24.07  " 

Lime                        1.32      « 

Vegetable  matter          72.39  " 

Magnesia                  .32      " 

Silfca                               4.31  " 

Four  specimens  contained  a  small  quantity  of  potash,  and 
one  specimen  contained  1.2  per  cent,  of  phosphate  of  magnesia. 
It  will  be  seen  that  peat  contains  a  large  quantity  of  vegetable 
matter  and  of  salts. 

2.  Sivamp  muck  consists  of  the  pairings  of  the  peat,  and  is 
less  compact.  It  is  found  in  every  meadow,  and  includes  the 
hassocks.  It  also  includes  the  variety  of  peat  which  has  be- 
come partially  decomposed,  and  the  mud  of  salt  marshes. 

3.  Pond  mud  is  found  at  the  bottom  of  ponds,  when  dry, 


BY  PEAT  MUCK  AND  POND  MUD.  305 

and  in  low  grounds.  It  consists  of  from  15  to  20  per  cent, 
of  vegetable  matter,  which  has  been  washed  down  from  the 
high  lands  and  mixed  with  earthy  materials.  Dr.  Dana  has 
given  the  composition  of  10  specimens  of  Massachusetts  peat 
and  swamp  muck,  dried  at  a  temperature  of  300°  F.  The 
average  quantity  of  ingredients  is  85  per  cent,  of  vegetable 
matter ;  of  which  29.46  is  soluble  and  55.03  is  insoluble  ; 
15.9  per  cent,  are  salts  and  silicates.  The  composition  of 
pond  mud  is  very  different,  only  5  to  8  of  insoluble  and  from 
6  to  9  per  cent,  of  soluble  vegetable  matter  or  geine.  The  salts 
of  lime,  however,  are  abundant,  being  about  2  per  cent.  It 
should  be  remarked  that  the  proportion  of  the  soluble  to  the 
insoluble  portion  is  much  greater  in  the  mud  than  in  the  peat^ 
and  hence  the  effects  of  this  substance  will  be  more  immedi- 
ate, but  not  so  lasting  as  peat  and  muck. 

When  peat  is  first  dry,  it  contains  from  78  to  98  per  cent, 
of  water.  In  drying,  it  shrinks  tv/o-thirds  or  three-fourths  of 
its  bulk.     When  green,  it  contains,  of 

Water  85.    I  Silicates  .5 

Salts  of  lime  .5  |  Humus  14.0 

looo 

If,  now,  we  estimate  the  value  of  fresh  dry  peat  as  compared 
with  cow  dung,  we  shall  find  that  the  two  substances  are  con- 
stituted almost  exactly  alike.  The  salts  and  the  geine  or  hu- 
mus, in  every  cord  of  peat,  are  equal  to  those  produced  by  the 
cow  in  three  months.  But  there  is  one  important  difference. 
The  cow  dung  is  capable  of  producing  a  large  quantity  of 
ammonia,  but  the  peat  only  contains  slight  traces  of  it.  Still 
there  is  found  crenic  and  apocrenic  acids,  which  may  serve 
the  purpose  of  the  ammonia,  by  yielding  their  nitrogen  in  the 
processes  of  vegetation. 

The  action  of  the  ammonia,  as  we  have  remarked,  is  to  in- 
duce decay  and  consequent  conversion  of  the  insoluble  geine 
or  humin  into  humic,  crenic  and  apocrenic  acids,  or  into  solu- 
ble geine.     If,  now,  there  is  any  process  of  adding  to  the 
26 


3Q(5  IMPROVEMENT  OF  THE  SOIL. 

peat  muck,  either  ammonia  or  any  substance  which  will  pro- 
duce the  same  effect,  we  may  convert  it  into  cow  dung, 
cord  for  cord.     This  may  be  done  in  the  compost  heap  m  the 

following  ways.  ,        c    u    v^ 

1    Compost  of  peat  tvith  alkalies.     The  action  of  alkalies 

upon  vegetable  matter,  to  induce  decay,  has  been  frequently 

referred  to.     The  action  of  all  are  alike  in  this  respect ;  but 

the  products  are  not  all  the  same,  and  it  becomes  a  question 

of  areat  practical  importance  what  alkali  to  use,  and  what 

quantity  to  employ,  in  order  to  produce  the  best  effect  with 

the  least  expense. 

The  alkalies  employed  to  decompose  the  peat,  and  convert 
it  into  cow  dung,  are  soda,  ammonia  and  potash. 

Ammonia  is  generally  too  expensive  an  article  for  h.s 
purpose.  In  other  respects  it  would  be  the  best,  as  all  that 
would  be  needed  would  be  to  add  about  2  lbs.  of  the  carbonate 
or  sulphate  to  every  100  lbs.  of  peat.  As  there  are  other  al- 
kalies in  the  peat,  1  lb.  in  practice  has  been  found  to  answer 
the  purpose.  Potash  and  soda  are  almost  the  only  alkalies 
which  can  be  obtained  in  sufficient  quantities,  and  at  a  pnce 
sufficiently  moderate  to  answer  the  wants  of  agriculture. 

In  order  to  determine  the  relative  quantit.es  of  the  above- 
named  substances,  it  will  be  necessary  to  resort  to  their  equiv- 
alents ;  1  part  of  ammonia  is  equal  to  2  of  soda,  and  2  parts  of 
soda  to  3  of  potash;  or  their  equivalents  are  nearly  as  the 
numbers  1,2,3.     But  these  alkalies  are  found  m  the  state  ot 
salts;  that  is,  combined  generally  with  carbonic  acid,  car- 
bonate of  ammonia  and  soda  or  wkitc  ash     These  are  about 
equal  in  their  effects,  while  pot  and  pearl  ash,  which  are  car- 
bonates of  potassa,  produce  but  about  two-thirds  the  effect^ 
Hence,  as  cow  dung  contains  2  per  cent,  of  ammonia,  if  we  add 
to  fresh  dry  peat  2  per  cent,  of  carbonate  of  ammonia,  2  of  soda 
ash,  or  3  per  cent,  of  potash,  they  will,  in  each  case,  convert 
it  imo  that  substance.      By  this  estimate,  as  eac^i  cord,  when 
dry   weighs  3216  lbs.,  it  would  require  84  lbs.  of  ammonia  or 


BY  COMPOST  MANURES.  307 

soda  ash,  or  276  lbs.  of  potash.  But  when  the  peat  is  dry,  it 
loses  nearly  three-fourths  of  its  bulk ;  and  hence  would  re- 
quire about  736  lbs.  of  soda  ash,  or  1104  lbs.  of  potash. 
These  proportions  are  found,  by  experiment,  to  effect  the  de- 
composition of  the  peat.  But  it  is  also  found  that  a  much 
less  quantity  of  alkali  will  convert  peat  into  cow  dung.  This 
is  probably  due  to  the  fact,  that  not  more  than  one-third  of 
the  ammonia  contained  in  cow  dung  is  active,  and  hence 
about  1  per  cent,  of  potash  will  be  sufficient  for  the  compost 
heap.  This  will  require  for  every  cord  oi  fresh  peat  92  lbs. 
of  potash,  or  61  lbs.  of  soda  ash,  or  16  bushels  of  common 
ashes. 

If  these  are  composted  together,  a  cord  of  the  compost 
ought  to  produce  effects  precisely  similar  to  cow  dung.  And 
experiments,  so  far  as  they  have  been  made,  seem  to  confirm 
the  theoretical  proportions.  But  a  smaller  quantity  of  alkali 
will  render  pe:it  a  very  valuable  manure  ;  20  lbs.  of  white  ash, 
or  30  of  potash  to  a  cord,  are  found  in  practice  to  be  as 
profitable  as  larger  quantities.  If  spent  ashes  are  used,  1  part 
of  ashes  to  3  of  peat  may  be  used. 

Care  should  be  taken  to  have  the  compost  heap  protected 
by  a  shed  or  a  thatch  of  straw,  and  worked  over  two  or  three 
times  before  carrying  it  upon  the  land.  In  the  process  of 
fermentation  which  takes  place,  nitrates  are  formed  and  other 
salts  of  a  highly  salutary  character. 

There  are  other  alkalies,  which  may  be  composted  with 
peat,  such  as  the  spent  lye  of  soap-manufacturers  and  lime. 
If  spent  ashes  are  used,  a  greater  or  less  quantity  of  lime  is 
also  added.  Some  regard  the  lime  which  the  ashes  contain  as 
less  likely  to  render  them  beneficial  in  their  effects.  But  if  lime 
and  common  salt  are  both  added  to  the  peat,  the  lime  will 
produce  effects  highly  beneficial. 

Take  one  bushel  of  salt  dissolved  in  water,  mix  it  with  a 
cask  of  slacked  lime,  so  as  to  make  them  into  a  thick  paste, 
and  let  them  remain  for  a  week.     This  may  then  be  mixed 


308 


IMPROVEMENT  OF  THE  SOIL 


with  three  cords  of  peat,  and  shovelled  over  for  about  six 
weeks,  and  than  applied  to  the  soil. 

Theory.  The  theory  of  the  changes  which  are  produced, 
may  be  known  from  the  elements  which  are  brought  together. 
The  salt  is  converted  into  soda  and  hydrochloric  acid.  When 
the  lime  is  brought  into  play,  the  acid  combines  with  it  and 
forms  a  soluble  salt ;  the  soda  acts  upon  the  peat,  evolves  its 
ammonia  as  above,  and  becomes  carbonated.  Mutual  decom- 
position of  the  carbonate  of  soda  and  muriate  of  lime  now 
takes  place,  and  carbonate  of  lime  in  minute  portions  is 
formed  throughout  the  mass,  ready  to  act  upon  the  silicates 
and  liberate  their  alkalies,  and  upon  the  geine,  while  the  soda 
and  muriatic  acid  are  so  combined  as  to  form  salt  again. 
Composts  of  this  description  may  be  formed  at  an  expense  of 
not  more  than  $2,25  per  cord,  and  are  believed  to  be  very 
effectual  manures. 

A  compost  may  be  formed  which  will  prove  effectual,  if 
the  above  does  not.  Add  61  lbs.  of  lime,  and  61  lbs.  of  sal- 
ammoniac  to  three  cords  of  peat,  and  an  article  will  be  form- 
ed, at  an  expense  of  less  than  $5,00  per  cord,  which  will  be 
fully  equal  in  value  to  common  yard  manure. 

2.  Composts  of  peat  with  animal  inatter.  Peat  and  swamp 
muck  may  be  decomposed  in  a  compost  heap  with  refuse  ani- 
mal matter.  '*  The  carcass  of  a  dead  horse,"  says  Lord  Mea- 
dowbank,  *'  which  is  suffered  to  pollute  the  air  with  its  effluvia, 
has  been  happily  employed  in  decomposing  20  tons  of  peat 
earth,  and  transforming  it  into  the  most  valuable  manure." 

Urine,  will  also  decompose  it  by  the  action  of  its  ammonia, 
and  other  salts ;  hence,  the  importance  of  having  peat  and 
swamp  muck  at  hand,  on  to  which  the  liquid  excretions  may 
be  poured.  In  some  countries,  as  in  Flanders  and  in  China, 
large  tanks  are  provided  into  which  the  urine  is  conducted, 
and  then  either  applied  in  the  liquid  state,  or  mixed  with 
loam  and  peat  earth.  "  Liquid  manures,"  says  Mr.  Young, 
*'  are  of  the  same  value  as  the  solid  •,  one  ton  of  solid  dung 


BY  COMPOST  MANURES.  309 

will  make  four  tons  of  compost,  and  four  tons  more  may  be 
made  by  the  urine  discharged  by  the  cattle  in  the  same  time." 

Night  soil  is  similar  in  its  effects.  Fish  also  make  an  ex- 
cellent compost,  if  lime  is  added  to  neutralize  the  acids  or 
combine  with  the  oils.  Any  refuse  animal  matter,  such  as 
woollen  or  cotton  waste,  and  the  washings  of  wool  from  wool- 
len factories,  may  be  mixed  with  peat  and  a  most  powerful 
manure  formed. 

3.  Compost  of  peat  with  green  manures.  We  have  al- 
ready described  the  process  of  preparing  yard  and  stable  ma- 
nure ;  underlaying  it,  and  covering  it  with  loam  or  peat  earth. 
The  direct  object  in  this  case  is  to  protect  the  manure,  and 
save  the  valuable  products  of  fermentation,  putrefaction,  etc. 
But  in  the  process  now  to  be  described,  the  object  is  to  de- 
compose the  peat,  by  means  of  the  ammonia  which  green 
manures  evolve.  The  quantity  of  ammonia  in  100  lbs.  of 
cow  dung  as  we  have  seen,  is  about  2  lbs.  This  is  sufficient 
to  convert  200  lbs.  of  peat  into  a  substance  of  equal  value 
with  cow  dung.  The  urine  which  is  mixed  with  stable  ma- 
nure will  more  than  double  this  quantity;  hence,  if  3  cords 
of  peat  are  mixed  with  one  of  stable  manure,  there  will  be 
formed  4  cords  of  manure  equal  in  value  to  cow  dung.  These 
proportions  agree  with  experience,  and  may  serve  to  confirm 
us  in  the  process,  which  has  been  recommended  by  practical 
farmers. 

Process.  In  order  to  prepare  a  compost-heap  with  green 
manures,  the  peat  should  be  dug  and  exposed  to  the  rains  for 
a  while,  to  be  deprived  of  its  tannin  and  acids ;  then,  when 
partly  dry,  it  may  be  carried  into  the  cattle-yard  or  shed,  or 
on  to  the  field,  and  mixed  with  green  manure.  A  layer  of 
peat  should  form  the  base  of  the  heap,  then  a  layer  of  manure, 
and  then  alternate  layers  of  peat  and  manure,  ending  with  a 
thick  layer  of  peat.  The  shape  should  be  conical,  and  cov- 
ered, if  exposed  to  rains,  with  a  thatch  o{  straw,  or  with  boards. 
If  lime  or  ashes  are  added,  they  will  facilitate  the  process  of 
26* 


310  IMPROVEMENT   OF   THE    SOIL 

decomposition.  The  heap,  in  the  course  of  six  weeks  or  two 
months,  may  be  shovelled  over  and  more  peat  added,  if  it 
is  still  in  a  state  of^  fermentation.  Some  recommend  the  ap- 
plication of  lime  at  the  time  of  shovelling  it  over,  in  order  to 
liberate  the  ammonia.  It  should  then  be  carried  directly 
upon  the  field. 

The  changes  which  take  place  are  similar  to  those  in  fer- 
menting dung-heaps.  The  result  is  the  same,  soluble  and  in- 
soluble geine  and  salts.  Lord  Meadowbank,  who  first  called 
attention  to  this  subject,  states  "  that  in  every  diversity  of 
soil,  it  has  given  returns,  in  nowise  inferior  to  the  best  barn- 
yard dung,  applied  in  the  same  quantity,  and  that  it  is  equal, 
if  not  preferable,  in  its  effects  for  the  first  three  years,  and 
decidedly  superior  afterward." 

The  testimony  of  several  New  England  farmers  who  have 
tried  this  compost,  is  that  *'  three  parts  of  peat  with  one  of  sta- 
ble manure,  make  a  compost  which  is  equal  in  value  to  its 
bulk  of  clear  stable-dung,  and  is  more  permanent  in  its  ef- 
fects." 

It  may  be  applied  to  any  soil,  either  in  the  hill,  or  spread 
broad-cast  and  turned  in ;  or  it  may  be  used  as  a  top-dressing 
upon  grass  lands.  In  the  absence  of  peat  and  swamp  muck, 
composts  may  be  formed  with  loam,  straw,  leaves,  or  any 
vegetable  matter,  which  will  absorb  the  gaseous  and  liquid 
products. 

The  quantity  of  peat  and  swamp  muck  in  the  eastern  part 
of  Massachusetts,  is  sufficient  to  render  all  her  barren  hills  as 
fertile  as  the  prairies  of  the  West.  The  only  difficulty  there 
is  in  the  case,  is  to  persuade  farmers  to  prepare  it,  and  apply 
it  to  their  soils. 

Methods  of  applying  manures.  It  has  been  a  question  of 
frequent  discussion,  whether  manures  should  be  applied  to 
land  in  the  green,  or  rotted  state.  The  best  answer  to  this 
question  is,  that  they  should  not  be  applied  in  either  state ;  but 
should  always  be  made  into  composts,  and  applied  after  fer- 


BY  COMPOST  MANURES.  311 

mentation ;  and  the  reason  is,  that  every  cord  of  clear  stable- 
dung  may  help  form  four  of  good  rotted  manure.  But  as 
farmers  will  continue  to  apply  their  manures  in  a  pure  state, 
a  few  rules  may  aid  them  to  do  it  in  the  best  manner. 

1.  For  cold,  stiff  or  wet  soils,  sheep  and  horse  manure  are 
the  best,  and  should  be  applied  in  the  green  state,  spread  up- 
on the  land,  and  immediately  turned  under. 

Theory.  The  reason  is,  that  such  soils  require  the  heat 
incident  upon  fermentation  of  the  manure.  And,  as  it  is  dif- 
fused through  the  soil,  the  roots  of  plants  feel  its  full  in- 
fluence. Such  manures  also  render  the  soil  lighter  and 
dryer. 

2.  For  light,  sandy  or  gravelly  soils,  hog  or  cattle  dung 
may  also  be  applied  in  the  green  state,  spread  and  ploughed  in 
as  above.  Horse  manure  should  be  fermented,  before  being 
applied  to  such  soils. 

Theory.  These  soils  do  not  require  the  heat,  and  a  less 
quantity  is  produced  in  fermentation  by  cattle  than  by  horse 
manure.  By  applying  it  in  the  green  state,  the  gaseous  pro- 
ducts are  saved,  and  one  third  of  the  manure ;  as  it  has  been 
found  by  experiment,  that  one  third  at  least,  is  wasted  in  pass- 
ing to  the  state  of  short  muck  in  cattle  yards. 

3.  Green  manures,  however,  should  never  be  applied  to 
any  but  a  hoed  crop.  If  wheat  or  rye  are  sown  on  lands  ma- 
nured at  all,  it  should  be  rotted  manure. 

Tlieory.  In  a  hoed  crop,  fermentation  is  most  active 
in  mid-summer,  when  the  stalks  and  leaves  need  its  influ- 
ence ;  but  in  a  grain  crop,  the  kernel  is  ripening  at  that 
period,  and  fermentation  is  injurious  to  the  process.  If  the 
straw  is  increased  by  the  large  quantity  of  carbonic  acid 
which  fermentation  produces,  the  harvest  will  be  hazarded  ; 
for  the  supply  of  food  to  the  grain  cannot  be  assimilated,  and 
disease  and  consequent  blight  will  ensue. 

4.  Rotted  manure  acts  with  greater  power  in  the  early 
part  of  the  season  than  green ;  and  hence,  farmers  generally 


312  IMPROVEMENT  OF  THE  SOIL 

prefer  it.  But  the  green  manure  shows  its  superior  effects  in 
the  harvest.  The  best  rule  is  to  apply  to  hoed  crops  a  small 
quantity  of  rotted  manure  in  the  hill,  to  give  the  young  plant 
a  vigorous  "  start,"  but  to  spread  the  greater  portion  in  a 
green  state,  to  act  upon  the  crop  in  mid-summer.  The  gen- 
eral practice  of  manuring  in  the  hill  is,  by  the  best  farmers, 
almost  wholly  discontinued. 

Sect.  5.  Saline  Manures,  or  those  consisting  of  inorganic 
Salts. 

Mineral  substances  act  as  manures,  when  they  enter  in- 
to the  composition  of  plants.  They  act  as  amendments 
or  correctors,  when  they  improve  the  texture  or  neutral- 
ize acids.  They  act  as  solvents  or  converters,  when  they 
induce  changes  in  animal  and  vegetable  bodies,  or  con- 
vert them  into  vegetable  food.  They  act  as  stimulants,  when 
they  excite  the  living  powers  of  plants  by  producing  electri- 
cal changes,  and  other  effects  not  well  understood. 

The  substances,  classed  as  mineral  manures,  are  salts ;  that 
is,  they  consist  of  acids  combined  with  alkalies,  alkaline 
earths  and  metallic  oxides.  As  fertility  depends  upon  salts 
and  geine,  and,  as  the  base  of  the  salt,  or  alkaline  portion, 
acts  wholly  upon  geine,  and  in  one  uniform  manner,  p.  220, 
salts  may  be  classed,  with  reference  to  the  peculiariti/  of  their 
influence,  by  their  acids. 

In  this  respect,  salts  may  be  divided  into  two  classes. 
1.  Those  salts  whose  acid  nourishes  plants ;  such  are  nitrates, 
carbonates  and  phosphates.  2.  Those  salts,  whose  acid 
poisons  plants,  or  yields  but  a  small  quantity  or  no  nutri- 
ment ;  such  as  sulphates,  hydrochlorates  or  muriates. 

I.  Salts  ivhose  acid  contains  the  elements  ivhich  nourish 
plants.  This  class  includes  three  families,  which  may  be  de- 
scribed as  nitrates,  phosphates  and  carbonates. 

I.  Nitrates.  In  this  family  of  salts,  nitric  acid  is  com- 
bined with  several  bases.      The  three  principal  salts  which 


BY  SALINE  MANURES.  313 

are  used  in  agriculture  are  those  of  ammonia,  potash  and  so- 
da. Nitrate  of  ammonia  is  formed  in  fermenting  dung 
heaps,  but  is  rarely  applied  artificially. 

Nitrate  of  potash,  or  nitre,  is  composed  of  54  parts,  by 
weight,  of  nitric  acid  (aquafortis)  and  47  of  potassa.  This 
substance  has  long  been  a  celebrated  saline  manure.  Its 
effects  are  not  only  powerfiil  but  permanent.  Upon  what 
does  its  utility  depend  ?  In  order  to  answer  this  inquiry, 
we  have  only  to  refer  to  principles  already  suggested. 

Every  100  lbs.  of  nitre  contain  about  46  of  potash.  This 
acts  only  upon  the  vegetable  matters  of  the  soil,  and  is  proba- 
bly let  loose  from  its  combination,  by  growing  plants  (by  ca- 
talysis). We  have  already  noticed  the  influence  of  potash 
upon  peat.  200  lbs.  of  nitre  would  furnish  potash  sufficient  to 
decompose  one  cord  of  peat  or  muck.  The  action  of  the  acid 
is  more  complicated.  It  contains  40  parts  of  oxygen  and  14 
of  nitrogen.  It  may  therefore  be  decomposed,  and  yield  nitro- 
gen and  oxygen  to  the  vegetable  products,  p.  16#/  But  its 
oxygen  probably  acts  both  upon  the  vegetable  matter  and  the 
silicates.  By  its  action  on  the  humus,  a  part  is  rendered 
soluble,  and  carbonic  acid  is  formed,  which  acts  upon  the 
silicates,  and  liberates  their  alkalies.  If  the  above  is  a  true 
representation  of  the  changes  which  take  place,  it  proves  that 
nitre  is  a  most  valuable  substance  to  be  applied  to  the  soil. 
Experiment  has  shown  that  100  or  150  lbs.  of  nitre,  per  acre, 
will  produce  the  most  gratifying  results.  It  may  be  spread, 
or  mixed  with  the  manures. 

Nitrate  of  soda  is  nitric  acid  combined  with  soda,  in  the 
proportion  of  54  parts  of  the  former  to  31  of  the  latter.  Its 
action  is  precisely  similar  to  nitre.  The  soda  acts  upon  veg- 
etable matter,  and  the  acid  indirectly  upon  the  silicates.  The 
quantity  applied  may  be  about  100  or  150  lbs.  to  the  acre, 
spread  broad-cast,  or  mixed  with  the  manures. 

The  above  substances,  including  nitrate  of  ammonia,  are 
the  food  of  vegetables,  and  hence  are  properly  classed  as  ma- 


314  IMPROVEMENT  OF  THE  SOIL 

nures.  There  is,  moreover,  no  danger  of  adding  them  in  too 
large  quantities.  They  are  nourishers,  and  their  action,  as 
salts,  does  not  produce  insoluble  compounds,  but  tends  to 
render  inert  bodies  active  and  useful.  The  nitrates  are  all 
exceedingly  mild,  although  very  active,  and  useful  in  their  in- 
fluence upon  vegetation. 

2.  Phosphates.  This  family  includes  substances  already 
considered,  such  as  bone,  earth,  horn,  hair,  hoofs,  etc.  The 
only  mineral  phosphates,  which  may  be  used  as  manures,  are 
phosphate  of  lime  (apatite)  and  phosphate  of  magnesia  ;  but 
these  substances  are  not  found  in  sufficient  quantities  to  ren- 
der their  application  practicable.  Phosphates  act  very  much 
like  nitrates,  the  acid  is  food,  and  exists  in  vegetables  Jn 
combination  with  magnesia.  It  also  acts  upon  silicates,  and 
eliminates  their  alkali. 

Bone  dust  is  principally  phosphate  of  lime,  and  is  a  highly 
concentrated  manure. 

3.  CMonates,  This  family  includes  common  limestone, 
marl  and  air-slacked  lime ;  potash,  ashes  and  white-ash  or 
barilla.  Carbonate  of  lime  is  known  under  the  names  of 
chalk,  shells,  marble,  marl,  limestone,  etc.  The  most  com- 
mon forms  in  which  it  is  used  in  agriculture,  are  shells, 
marl  and  air-slacked  lime;  although  ground  limestone  has 
sometimes  been  applied  to  fertilize  the  soil.  Salts  of  lime 
have  long  been  used  for  agricultural  purposes.  Their  bene- 
ficial effects  were  known  to  the  ancients.  They  have  been 
used  in  England,  France  and  Germany  for  the  last  100  years, 
with  the  very  best  results,  and  yet  practical  farmers  are  not 
all  agreed  whether  lime  is  useful  or  hurtful  in  its  effects. 
Experience  shows  that  it  is  sometimes  injurious  and  at  others 
highly  beneficial.  Any  theory,  therefore,  which  shall  enable 
us  to  decide  the  quantity  which  may  be  safely  used  (for  it  ap- 
pears that  the  bad  or  good  effects  depend  mostly  upon  the 
quantity  employed),  must  be  of  the  highest  benefit  to  the 
practical  farmer. 


BY  SALINE  MANURES.  315 

Theory.  Carbonate  of  lime  acts  like  all  saline  compounds ; 
the  base  is  let  loose,  by  the  action  of  the  living  plant,  and 
acts  in  its  caustic  state  upon  insoluble  vegetable  matter,  and 
converts  it  into  vegetable  food.  The  carbonic  acid  acts  upon 
the  silicates  and  obtains  the  potash  and  soda,  which  react  up- 
on the  humus,  and  render  larger  portions  of  it  soluble.  The 
action  is  slow,  but  the  effects  are  sure. 

When  lime  is  applied  in  a  caustic  state,  it  slowly  absorbs 
carbonic  acid,  and  becomes  a  carbonate.  If  a  large  quanti- 
tity  is  used  it  may  form  a  super-salt  with  humic  acid,  and 
become  inert  because  insoluble.  It  is  in  this  way  that  it 
proves  injurious.  But  this  state  cannot  always  last,  for  the 
salt  will,  in  time,  be  decomposed  and  rendered  useful. 

When  acids  exist  in  the  soil,  both  the  caustic  and  carbon- 
ate of  lime  tend  to  neutralize  their  effects  ;  hence  it  aj^ears 
that  the  base  of  lime  acts  in  a  four-fold  capacity,  as  a  con- 
verter, a  ncutralizer,  a  decomposer,  and  a  retainer.   ,  > 

(1)  Lime  acts  as  a  converter,  when  it  convertajlpsgetable 
fibre  into  vegetable  food.  This  appears  to  be  the  most  im- 
portant use  of  lime,  and  the  most  difficult  to  explain.  It  has 
been  referred  to  its  "  catalytic"  power  or  to  the  action  of 
presence,  but  whatever  may  be  the  nature  of  the  force,  it  is 
well  established,  that  when  lime  is  brought  into  contact  with 
vegetable  matter,  it  hastens  its  decay.  The  humic  or  geic 
acid  thus  formed  combines  with  it,  and  becomes  a  soluble 
salt,  ready  to  enter  the  vegetable  organs. 

(2)  Lime  acts  as  a  neutralizer,  whenever  acids  exist  in 
the  soil  in  a  free  state.  Some  soils  are  called  acid  soils,  and, 
as  the  carbonic  acid  is  displaced  by  most  other  acids,  the 
lime  will  combine  with  the  acid  and  neutralize  its  effects. 
Peat  and  smamp  muck  often  contain  acids,  which  may  be 
neutralized  in  this  way  ;  hence  lime  should  be  applied  to  peat 
earth,  before  it  is  used. 

(3)  Lime  acts  as  a  decomposer,  when  it  decomposes  any 
inert  or  injurious  substance  in  the  soil,  as  metallic  salts.    Veg- 


316  IMPROVEMENT  OF  THE  SOIL 

etable  matter  forms,  with  alumina,  a  substance  which  is  per- 
fectly inert  and  useless  (humate  or  geate  of  alumina).  Lime 
will  decompose  it,  and  form  a  soluble  salt  (humate  or  geate 
of  lime). 

Sulphate  of  iron,  or  copperas,  exists  also  in  many  soils,  and 
is  highly  poisonous  in  its  influence ;  lime  will  decompose  this 
salt,  and  form  sulphate  of  lime,  or  plaster,  an  effective  ma- 
nure. 

As  lime  soon  becomes  carbonated  in  the  soil,  if  applied  in 
a  caustic  state,  its  action  is  nearly  the  same  as  when  applied 
as  marl  or  ground  carbonate.  In  both  cases,  the  acid  acts 
upon  the  silicates,  and  decomposes  them,  hence  lime  will  de- 
compose the  silicate  of  potash  in  spent  ashes,  and  render  the 
the  alkali  active. 

(4)  Lime  acts  as  a  retainer  when  it  forms  super-salts  with 
humic,  crenic  and  apocrenic  acids.  It  thus  locks  up  the 
vegetable  matters,  which  it  has  converted  into  food,  and  this 
is  one  rOTison  of  its  injurious  effects.  Still  the  matter  is  re- 
tained and  will  in  the  end  all  be  appropriated.  This  effect 
must  take  place  whether  the  quantity  is  large  or  small ;  but 
if  there  is  a  small  quantity  of  vegetable  matter  in  the  soil,  a 
large  quantity  of  lime  should  not  be  applied.  We  have  here 
a  solution  of  the  mystery  relative  to  the  effects  of  lime. 

If  lime  is  added  in  large  quantities,  and  in  a  caustic  state, 
it  induces  decay  of  the  humus,  and  the  formation  of  carbon- 
ic acid.  It  combines  with  both  of  the  products,  and  if  the 
proportion  of  vegetable  matter  is  small,  it  will  form  so  large 
a  quantity  of  it  into  super-salts,  as  to  injure  the  crop  ;  hence 
it  may  be  concluded,  1.  That  lime  is  useless  on  soils  destitute 
of  vegetable  matter,  and  that  it  will  not  render  them  capable  of 
sustaining  vegetation.  2.  That  lime  is  often  injurious  on  soils 
containing  but  a  small  quantity  of  vegetable  matter.  3.  That 
lime  is  highly  useful,  when  applied  to  soils  containing  a  large 
proportion  of  humus.     If  therefore,  lime  is  applied  to  soils, 


BY  SALINE  MANURES.  317 

vegetable  matter  must  also  be  added,  to  ensure  its  good  ef- 
fects. 

The  utility  cf  lime  in  agriculture,  when  properly  applied, 
is  well  established  by  experience.  The  quantity  required  is 
small,  one  per  cent.,  and  even  twelve  bushels  to  the  acre,  are 
valuable  additions.  "  A  quantity  of  lime,"  says  Mr.  Puvis, 
"  which  does  not  exceed  the  thousandth  part  of  the  tilled 
surface  layer  of  the  soil,  a  like  proportion  of  drawn  ashes,  or 
a  two-hundreth  part,  or  even  less  of  marl,  are  sufficient  to 
modify  the  nature,  change  the  products,  and  increase  by  one 
half,  the  crops  of  a  soil  destitute  of  the  calcareous  principle." 
Sir  John  Herschel  found  that  minute  portions  of  calcareous 
matter,  "  in  some  instances  less  than  the  millionth  part  of  the 
whole  compound,  are  sufficient  to  communicate  sensible  me- 
chanical motions,  and  definite  properties  to  the  bodies  with 
which  they  are  mixed."  As  such  effects  seem  to  be  electrical 
in  their  character,  we  may  conclude  that  there  is  a  fifth  office 
of  lime,  to  act  as  a  5#/;?m/«?«#,  by  developing  electrical  cur- 
rents. Upon  the  whole,  we  should  prefer  potash  to  lime,  but 
the  latter  is  unquestionably  beneficial  in  its  action,  and  may 
be  applied  in  small  quantities,  as  a  cask  to  an  acre,  without 
any  fear  of  injury,  and  with  the  certainty  of  ultimate  benefit. 

Carbonate  potash.  Potash  is  a  carbonate,  that  is,  it  con- 
sists of  carbonic  acid  combined  with  potassa.  The  action  of 
the  potash  has  already  been  considered,  p.  306.  It  is  some- 
times applied  to  the  soil  from  100  to  150  lbs.  to  the  acre. 
But  the  form  in  which  it  is  usually  applied  is  that  of 

Ashes.  The  value  of  ashes  depends  upon  the  kind  of  wood 
from  which  they  are  derived.  Those  fi-om  hard  wood  are 
more  valuable  than  those  from  soft. 

One  hundred  parts  of  hard  wood,  such  as  dry  oak,  beach, 
birch,  etc.  yield  2.87  parts  of  ashes.  One  hundred  parts  of 
dry  pine  yields  only  00.83  of  ashes,  while  100  parts  of  wheat 
straw  affords  0.44  per  cent.  The  ashes  consists  of  two  parts, 
soluble  and  insoluble  portions. 
27 


318  IMPROVEMENT  OF  THE  SOIL 

One  hundred  parts  of  the  soluble,  from  hard  wood,   are 
composed  of 

Carbonic  acid  22.70  I  Potash  and  soda  67.G6 


Sulphuric  acid  64^ 

Muriatic  acid  1.82  \  99.86 

Silex  .!!5  I 

It  will  be  perceived  that  the  salts  are  not  all  carbonates, 
although  the  greater  proportion  of  them  are.  One  hundred 
parts  of  the  insoluble  portions  contain 


Carbonic  acid 

35.80 

Oxide  of  manganese 

2.15 

Phosphoric  acid 

3.40 

Magnesia 

3.55 

Silex 

4.25 

Lime 

35.80 

Oxide  of  iron 

.52 

Peat  ashes  contain  carbonate,  phosphate  and  sulphate  of 
lime. 

Ashes,  then,  are  composed  of  salts  and  silicates  ;  they  con- 
tain potash,  lime  and  soda,  and  their  use  depends  upon  the 
action  of  these  alkalies,  which  render  them  an  efficient  ma- 
nure. Ashes  are  excellent  for  grass  lands.  One  bushel  of 
ashes  contains  5J  lbs.  of  potash,  a  quantity  sufficient  to  de- 
compose 200  lbs.  of  peat  earth. 

Leached  ashes  correspond  to  the  insoluble  portions,  and 
part  of  the  lime  is  added,  one  peck  of  lime  to  a  bushel  of 
ashes,  to  render  the  lye  caustic  by  absorbing  the  carbonic 
acid.  Spent  ashes,  however,  generally  contain  about  50  lbs. 
of  silicate  of  potash  per  cord,  so  that  they  act  both  by  their 
alkali  and  by  their  lime.  Silicate  of  potash  depends  for  its 
action  wholly  upon  being  converted  into  the  carbonate  of 
potash,  and  hence  may  be  classed  with  the  carbonates. 

When  ashes  are  composted  with  peat,  they  form  a  cheap 
and  valuable  manure;  but  should  not  be  applied  to  the  soil 
in  large  quantities,  unless  vegetable  matters  are  also  added. 
Ashes  applied  to  light,  dry  soils,  always  act  beneficially.  On 
wet  soils,  they  sometimes  introduce  mosses. 

Barilla  or  white  ash,  may  be  classed  as  a  carbonate ;  its 
has  already  been  considered,  p.  367.     The  latter  may 


BY  SALINE  MANURES. 


319 


be  applied  to  the  soil,  100  lbs.  to  the  acre,  with  the  most  per- 
fect confidence  in  its  utility.  The  former  contains  carbon- 
ate of  lime,  about  half  of  its  weight,  with  carbonate  of  soda. 
The  ashes  from  antharcite  coal  contain  carbonate  of  lime,  al- 
umina and  oxide  of  iron,  and  are  useful  saline  manures. 
Ashes  of  all  kinds  are  particularly  useful  on  grass  lands. 
Peat  ashes  contain  so  much  gypsum  that  they  generally  act 
with  greater  power  than  those  from  wood. 

II.  Salts  whose  add  does  not  enter  into  the  composition  of 
plants,  and  which  is  poisonous.  This  division  includes,  1. 
Sulphates,  such  as  sulphate  of  lime,  iron,  potash  and  soda. 
2.  Muriates  or  chlorides,  as  common  salt,  chloride  of  calcium, 
and  of  potassum. 

1.  Sulphate  of  lime,  or  plaster,  has  long  been  used  as  a  sa- 
line manure.  It  has  been  proved  by  experiment,  that  "  a 
bushel  of  plaster  per  acre,  or  even  the  one  four-hundreth  part 
of  one  per  cent,  produces  effects  on  alluvial  land,  which  shows 
its  good  results,  as  far  as  the  eye  can  reach."  This  effect 
can  be  explained  :  on  the  supposition  that  plants  decom- 
pose the  salt,  and  let  loose  the  lime  upon  the  geine ;  the  acid 
must  act  upon  the  silicates,  and  form  sulphates  of  potash,  of 
soda,  and  (if  silicate  of  lime  exist)  of  lime.  In  this  way  the 
plaster  reproduces  itself. 

Plaster  has  been  found  in  some  plants.  It  is  supposed  by 
Liebig,  to  act  chiefly  by  condensing  ammonia,  and  retaining 
it  for  the  wants  of  vegetation. 

Sulphate  of  iron,  or  copperas,  is  not  applied  to  any  but  a 
calcareous  soil,  and  the  result  is  the  formation  of  gypsum, 
by  the  action  of  lime  to  decompose  the  copperas. 

2.  Chlorides.  Common  salt  is  beneficial  upon  some  soils ; 
it  acts  by  the  soda  which  it  contains.  Thirty  bushels  to  the 
acre,  has  produced  good  effects.  It  may  be  best  employed 
for  composts. 

Spent  lye  from  soap-works  has  already  been  considered. 
In  all  cases,  the  action  of  salts  depends  upon  the  presence 


320 


IMPROVEMENT  OF  THE  SOIL 


of  life.  A  living  plant  introduced  into  the  soil,  causes  all  the 
chemical  forces  to  strive  together  to  supply  the  necessary  con- 
ditions for  the  perfection  of  the  vegetable  productions. 

Application  of  saline  jnanurcs.  The  quantity  of  salts 
used  on  any  soil,  must  be  determined  chiefly  by  experiment. 
The  following  are  the  conclusions  of  M.  Lecoq,  who  publish- 
ed the  result  of  his  experiments  in  his  Prize  Essay,  1832. 

**  1.  Salts,  so  far  as  possible,  should  be  used  in  powder. 

2.  If  used  in  solution,  they  must  be  diluted  with  a  large 
quantity  of  water. 

3.  Saline  manures  may  be  advantageously  used  on  all  soils. 

4.  They  answer  best  on  light  and  dry  soils. 

5.  They  produce  good  effects  on  wet  meadows,  but  must 
be  used  in  large  quantities. 

6.  It  is  preferable  to  spread  salts  at  two  epochs,  in  order  to 
increase  their  action. 

7.  Some  soils,  especially  those  where  mineral  springs  ex- 
ist, and  those  around  volcanoes,  are  already  charged  with  a 
sufliciency  of  saline  matter. 

8.  In  too  large  quantities,  saline  matters  injure  vegetation. 
In  too  small  quantities,  they  have  no  action. 

9.  The  proportions  that  give  the  best  results,  are  from  150 
to  330  lbs.  to  the  acre. 

10.  One  hundred  and  fifty  pounds  to  the  acre  is  the  best 
proportion  for  grazing  lands  and  meadows. 

11.  These  proportions  must  be  varied  with  the  nature  of 
the  soil ;  and  150  to  250  lbs.  per  acre,  is  generally  the  best 
quantity  for  light  soil,  but  may  be  increased  to  300  lbs.  on 
mowing  lands,  and  even  to  GOO  lbs.  on  wet  meadows,  where 
we  may  use  double  this  amount  without  injury  to  vegetation. 

12.  These  are  the  proportions  for  sea  salt  and  muriate  of 
lime  ;  they  should  vary  with  the  other  salts. 

13.  Fishery  salt  is  prefered,  as  it  is  cheaper. 

14.  Sulphate  of  soda  may  be  used  in  quantities  from  300 
to  600  lbs.  per  acre. 


BY  SALINE  MANURES.  321 

15.  Acetate  of  lime  exercises  but  little  action  on  plants  in 
quantities  below  300  lbs.  to  the  acre,  and  above  this  amount 
is  injurious. 

16.  Ammoniacal  salts  exert  a  very  marked  action  on  vege- 
tation, and  may  be  employed  in  the  quantities  of  150  lbs.  of 
the  sulphate,  or  100  lbs.  of  the  carbonate,  per  acre. 

17.  Sea  salt,  in  certain  cases,  may  replace  gypsum  in 
artificial  meadows ;  150  lbs.  of  salt  being  equal  to  5000  of 
gypsum. 

18.  Nitrate  of  potash  increases  considerably  the  crop,  when 
used  in  quantities  of  150  to  200  lbs.  per  acre. 

19.  The  best  time  for  spreading  the  salts  is  when  the 
young  plants  begin  to  put  forth  their  leaves.  At  the  epoch 
of  germination  they  are  more  injurious  than  useful. 

20.  Salts  do  not  favor  the  production  of  seed,  unless  asso- 
ciated with  organic  manures. 

21.  They  retard  the  maturity  of  plants,  and  give  more  de- 
velopment to  the  foliage,  thus  opposing  evaporation  of  the 
liquids  which  they  contain. 

22.  Burning  the  soil  may  be  regarded  as  belonging  to  the 
class  of  saline  manures,  since  salts  are  formed  with  the  or- 
ganic matters  that  the  soil  contains,  and  exert  a  very  marked 
influence  on  vegetation." 

This  last  means  of  obtaining  salts  may  be  practised  upon 
peat  meadows,  where  there  is  a  large  quantity  of  peat.  The 
surface  may  be  pared  with  a  plough  made  for  the  purpose, 
and  the  turf  collected  in  heaps  and  burned.  Then  by  spread- 
ing the  ashes,  the  peat  will  be  rapidly  converted  into  vegeta- 
ble food.  This  practice,  however,  should  not  be  resorted  to, 
unless  there  are  acids  in  the  peat,  or  a  large  quantity  of  land 
containing  peat.  The  vegetable  matter  is  more  profitably 
employed  for  composts.  Salts  may  be  obtained  generally  at 
a  cheaper  rate,  than  to  burn  manure  in  order  to  obtain  them. 

In  conclusion,  we  would  impress  it  upon  the  mind  of  the 
New  England  farmer,  that  the  preparation  and  proper  appli- 
27* 


322  IMPROVEMENT  OF  THE  SOIL 

cation  o^  manures,  are  the  sources  upon  which  he  must  main- 
ly rely  for  success  in  his  profession.  If  all  other  subjects  are 
disregarded  which  are  here  discussed,  let  him  not  neglect 
this ;  for  if  this  subject  is  properly  attended  to,  the  rest  will 
follow  in  its  train. 

Sect.  6.  Improvement  of  the  Soil  hy  Tillage. 

By  the  term  tillage,  we  mean  those  operations,  which  ap- 
ply directly  to  the  cultivation  of  farm  crops.  It  includes  the 
processes  of  ploughing,  harrowing,  rolling,  hoeing  and  weed- 
ing. These  processes  belong  to  all  kinds  of  tillage,  whether 
intended  to  improve  the  soil,  or  to  exhaust  it. 

We  have  already  considered  these  operations  in  their  re- 
lation to  vegetation.  In  this  section  these  processes  are  con- 
sidered with  reference  to  their  influence  upon  the  soil.  But 
as  the  treatment  is  the  same,  whichever  object  is  immediate- 
ly to  be  pursued,  only  a  few  remarks  need  be  added  to  those 
which  have  been  made  in  the  first  chapter. 

The  great  object  of  tillage  is  to  render  the  soil  light,  to 
promote  the  circulation  of  air  and  water,  a  free  extension  of 
the  roots  of  plants,  to  facilitate  the  chemical  changes  in 
the  soil,  and  an  equal  distribution  of  the  manures.  The  ope- 
rations of  ploughing,  harrowing,  hoeing,  etc.  have  already 
been  referred  to,  and  our  limits  forbid  any  further  remarks 
in  this  connection.     These  implements  need  no  description.* 

Fig.  18.  The  utility  of  the 

roller  (Fig.  14.) 
depends  upon  the 
fact  that  intersti- 
ces or  pores  are 
left  after  plough- 

*  Ploughs  are  now  manufactured  by  Nourse,  Ruggles  &  Mason, 
Boston,  which  perform  tliis  part  of  tillage  in  a  very  superior  manner. 


BY  TILLAGE.  323 

ing,  or  the  frosts  of  winter,  which  expose  the  roots  of  plants 
to  injury.  The  roller  breaks  down  the  lumps,  and  gives 
compactness  to  the  whole  mass.  The  good  effects  of  passing 
the  roller  over  fields  of  winter  grain  or  grass  lands  in  the 
spring,  have  been  fully  tested  by  experience.  The  earth, 
which  the  frost  has  rendered  porous,  and  which  does  not 
therefore  embrace  the  roots,  is  rendered  more  com  pact.  On 
light  sandy  soils,  the  use  of  the  roller  is  almost  indispensable,  by 
closing  the  pores  and  preventing  the  evaporation  of  the  mois- 
ture, which  such  soils  most  require,  although  they  are  more 
liable  than  any  other  to  yield  it  up. 

Fig.  19. 
The  utility  of  the 
cultivator  (A.  Fig. 
19),    may  also  be 
referred  to,  as  this 
implement  may  be 
employed   to   save 
the  labor  of  hoeing. 
It  also  leaves  the  ground  in  a  better  state  than  the  plough, 
when  used  among  hoed  crops.      But  it  is  not  our  purpose  to 
describe  the  instruments  of  tillage. 

We  may  observe,  in  conclusion,  that  thorough  ploughing, 
harrowing,  hoeing,  weeding,  etc.  will  incorporate  the  ma- 
nures with  the  earthy  ingredients,  and  promote,  in  the  best 
manner,  the  influence  of  all  those  atmospherical  and  other 
agents  which  are  required  to  Jit  the  soil  to  sustain  a  vigorous 
and  healthy  vegetation.  It  is  hardly  necessary  to  add,  that 
the  ease  of  cultivation  and  the  quantity  and  quality  of  produc- 
tions, will  depend,  materially,  upon  the  faithful  and  season- 
able performance  of  this  branch  of  the  art  of  husbandry. 


324  PRACTICAL  AGRICULTURE. 

CHAPTER  VIII. 

PRACTICAL    AGRICULTURE. 

Under  the  head  of  practical  agriculture  we  wish  to  in- 
clude the  modes  of  cultivating  the  farm  crops;  the  charac- 
ter and  value  of  each  species  of  grass,  grain  and  root,  which 
are  usually  cultivated  by  our  farmers.  As  these  modes  of 
culture  are  derived  from  experience,  an  opportunity  will  be 
afforded  of  testing  the  truth  of  many  principles  discussed  in 
the  preceding  chapters.  This  subject,  however,  must  be 
treated  in  a  concise  and  general  manner.  We  shall  present 
the  views  of  practical  farmers,  and  attempt  to  show  their  con- 
sistency with  scientific  principles.  Another  topic  under  this 
head  will  be  the  relation  of  farm  stock  to  the  cultivated  crops, 
a  few  suggestions  upon  which  will  close  the  chapter. 

Sect.  1.  Cultivation  of  Grains. 

The  following  are  the  most  important  cultivated  grains : 
Indian  corn,  oats,  barley,  rye  and  wheat. 

I.  Indian  corn,  or  zea  mais,  is  a  native  of  this  country,  and 
was  unknown  toEuropeans  until  after  the  discoveryof  America. 
In  consequence  of  the  different  climates  and  soils  in  which  it  has 
been  cultivated  for  a  long  series  of  years,  there  have  been  pro- 
duced several  varieties,  differing  more  in  appearance  and  hab- 
its than  many  distinct  species  of  plants.  We  know  how 
some  of  these  varieties  are  produced,  and  this  may  instruct 
us  in  the  selection  of  the  seed,  in  order  to  improve  any  par- 
ticular variety,  or  to  obtain  a  new  one.  One  mode  of  obtain- 
ing varieties  of  corn,  is  by  selecting  the  seed.  Thus,  for 
example,  a  celebrated  variety  has  been  produced  in  the  South- 
ern and  Western  States,  by  selecting  the  first  year  the  seed 
from  stalks  which  bore  two  ears,  and  taking  the  top  ear  to 
plant.     The  second  season  there  were  some  stalks  of  three 


CULTIVATION  OF  CORN.  '  325 

ears ;  and  the  top  ears  from  these  were  then  taken  and 
planted  ;  and  this  process  was  continued  for  a  series  of  years. 
The  consequence  was,  that  the  stalk  became  very  high  ;  and 
the  number  of  ears  upon  a  stalk  increased  from  one  to  five, 
and  even  eight.  It  should  be  remarked,  that  though  this 
process  gave  a  distinct  variety,  yet  it  would  have  been  a 
much  more  valuable  variety,  in  this  case,  if  the  lower  ears 
had  been  taken  ;  by  which  means  the  stalks  would  have  been 
lower,  the  ears  nearer  the  ground,  and  hence  much  less  liable 
to  injury,  and  more  likely  to  be  early,  plump  and  well  filled. 
By  the  selection  of  seed,  also,  an  early  or  late  variety 
may  be  obtained.  Thus,  for  example,  if  those  ears  which 
ripen  first,  are  selected  from  year  to  year  for  seed,  in  the 
course  of  eight  or  ten  years  an  early  variety  may  be  obtained ; 
and  if  those  ears  which  ripen  last  are  taken,  under  similar 
circumstances,  a  late  variety  may,  in  like  manner,  be  ob- 
tained. Hence,  in  the  selection  of  seed,  the  farmer  should 
consider  what  variety  he  wishes  to  obtain.  In  the  Eastern 
States,  an  early  crop  is  desirable.  In  the  Southern  States  a 
late  crop.  The  number  of  rows  on  an  ear  depends  upon 
similar  treatment.  Some  prefer  eight-rowed,  others  twelve 
or  more.  All  these  varieties  may  be  produced  by  selection 
of  seed  and  proper  culture. 

The  seed  corn  should  be  selected  in  the  autumn,  before 
harvesting,  and  hung  up  by  the  husks.  Before  planting,  it 
is  a  good  practice  to  soak  it  for  twenty-four  hours  in  cop- 
peras-water or  brine,  as  this  will  facilitate  germination  and 
prevent  the  wire-worm  from  eating  it  up. 

Soil.  The  soil  for  Indian  corn  should  be  a  light  sandy  or 
gravelly  loam.  A  rich  dry  soil  is  always  to  be  prefered.  In 
heavy  moist  soils,  it  will  not  flourish  as  well  as  potatoes  and 
most  other  hoed  crops.  It  should  be  planted  after  grain 
crops  or  clover.  Corn  may  be  manured  in  the  hill  with 
compost  or  rotted  manure.  It  is  much  better,  however,  to 
spread  green  manure  or  compost,  and  turn  it  into  the  soil. 


326  PRACTICAL  AGRICULTURE. 

The  corn  may  then  be  planted  in  rows,  about  three  feet  apart, 
and  from  five  to  six  kernels  in  a  hill,  lightly  covered  with 
loam.  It  is  desirable  in  theory  to  spread  fifteen  or  twenty 
loads  of  green  manure  to  the  acre,  and  turn  it  under,  to  act 
upon  the  crop  late  in  the  season,  and  then  to  put  five  or  six 
loads  of  compost  in  the  hill,  to  give  it  an  early  start ;  this 
corresponds  with  the  experience  of  the  best  farmers. 

The  after  culture  consists  in  two  or  three  hoeings,  or  one 
cleaning  with  the  cultivator  and  two  hoeings.  The  first  hoe- 
ing should  remove  the  earth  from  the  roots;  the  second 
should  raise  it  into  the  form  of  broad,  flat  hills.  Some  ex- 
periments, however,  seem  to  prove  that  corn  is  best  cultivated 
on  a  flat  surface,  with  a  tillage  depth  of  from  six  to  twelve 
inches ;  and  theory  would  lead  us  to  the  same  conclusion. 
The  practice  of  making  hills,  injures  the  roots  and  exposes 
them  to  the  influence  of  drought. 

The  modes  of  harvesting  corn  are  various.  Judge  Buel, 
after  repeated  experiments,  recommends  the  practice  of  cut- 
ting it  up  by  the  roots,  and  shocking  it  in  the  field,  when  the 
kernel  has  become  glazed,  so  as  to  yield  but  little  juice  when 
broken  open,  and  while  the  leaves  are  still  green.  We  must 
confess  that  this  practice  has,  upon  the  whole,  more  reasons 
in  favor  of  it  than  any  other. 

It  saves  labor ;  for  the  expense  of  cutting  and  securing  an 
acre  is  not  more  than  that  of  topping  it. 

It  adds  to  the  ciuantity  of  grain ;  because,  when  the  tops 
are  removed,  the  nourishment  which  would  go  to  the  kernel 
is  cut  off;  while,  by  letting  the  whole  stand  for  a  ^&w  days, 
and  then  cutting  it  up  by  the  roots,  the  process  of  assimilation 
will  continue  to  go  on  for  three  or  four  days  afterward. 

It  increases  the  quantity  of  fodder  and  preserves  its  nutri- 
tious properties ;  for  it  is  not  exposed  so  directly  to  the  influ- 
ence of  the  weather,  and  a  larger  quantity  of  the  green  parts 
is  preserved.     And,  finally,  it  yields  more  manure  and  is  se- 


CULTIVATION  OF  WHEAT.  327 

cured  against  early  frosts  ;  for  if  it  is  cut  when  it  is  full  in 

the  milk,  it  will  ripen  in  the  shock. 

The  expense  of  this  crop,  and  the  value  of  its  proceeds, 

may  be  estimated  as  follows. 
Ploughing,  4,00    I    Produce,   35  bushels,         $35,00 

Manure,  12,00         Corn   fodder,  lo  00 

$45,00 

28,75 

Profit,        $16,25 


Furrowing,  ,75 

Planting,  1,50 

First  hoeing,  2,50 

2d  and  3d  hoeing,  4,00 

Gathering,  2,00 

Husking,  2,00 


,75 


This,  we  think,  is  a  very  low  estimate  of  the  value  of  this 
crop  ;  for  the  manure  ought  not,  all  of  it,  to  be  charged  to  the 
corn,  as  it  generally  suffices  for  two  more  crops.  And  al- 
though the  average  may  not  be  more  than  35  bushels  to  the 
acre,  still  40,  50,  60  or  even  120  bushels  are  often  obtained 
m  the  Northern  and  Middle  States,  and  in  some  cases  170 
bushels  in  the  South  and  West. 

Broom-corn  is  cultivated  to  a  considerable  extent  in  the 
valley  of  the  Connecticut  river,  and  is  a  very  profitable  crop. 
The  particular  mode  of  its  cultivation  is  not  a  matter  of  gene- 
ral interest.  It  is  a  crop  which  yields  a  great  amount  of 
matter  ;  but  as  it  rarely  matures  its  seeds,  it  does  not  ordina- 
rily exhaust  the  soil  as  much  as  Indian  corn. 

2.  Wheat  has  been  cultivated  from  the  most  remote  an- 
tiquity. With  us,  two  species  are  known,  winter  wheat  {triti- 
cum  hybermim)  and  summer  wheat  [triticum  astivum). 

The  grain  itself  appears  under  two  varieties,  the  flint  or 
dark  colored,  and  the  white  or  thin-skinned.  Some  varieties 
are  bearded,  and  others  are  bald.  The  white  soft-skinned 
varieties  succeed  best  in  dry  soils  and  warm  climates;  the 
red  and  flint  varieties  prefer  a  moist  soil,  and  a  cool  tempera- 
ature. 

In  selecting  seed  wheat,  any  variety  may  be  improved ; 
and  It  has  been  found  that  the  best  method  is  to  go  into  the 


328  PRACTICAL  AGRICULTURE. 

field  when  it  is  fully  ripe,  and  select  the  longest  and  fullest 
heads,  from  which  seed  loheat  may  he  raised  the  folloicing  year. 
If  this  course  is  pursued,  the  crops  will  constantly  increase  in 
value. 

The  quantity  of  seed  \)et  acre  for  winter  wheat,  may  be  one 
bushel  and  a  half,  if  sowed  in  September  so  that  the  stalks 
may  spread  themselves.  If  sown  in  the  spring,  at  least  two 
bushels  per  acre  should  be  employed. 

The  soil  for  wheat  should  be  a  deep  loam,  perfectly  fine, 
dry  and  light;  containing  a  good  proportion  of  clay  and  car- 
bonate of  lime.  It  should  be  thoroughly  and  deeply  pul- 
verized. 

Wheat  should  not  be  sown  on  green  manure,  but  a  clover 
ley,  or  a  potato  crop  the  previous  year  is  the  best  prepara- 
tion. 

The  depth  at  which  it  is  sown  should  be  two  inches,  un- 
less the  land  is  very  finely  pulverized;  in  which  case  it  will 
flourish  much  better,  if  it  is  placed  only  one  inch  below  the 
surface.  The  ground  must  be  thoroughly  drained,  and  if 
the  sub-soil  plough  is  used,  it  will  very  much  increase  the 
value  of  the  crop.  Wheat  requires  phosphates  and  substan- 
ces rich  in  nitrogen.  It  will  therefore  be  improved,  by  add- 
ing to  the  soil,  salts  of  ammonia,  lime,  clay,  saltpetre  or 
bone  manure. 

There  is  nothing  worthy  of  notice  in  the  mode  of  harvesting 
this  crop.  It  should  be  left  standing  until  the  grain  is  fully 
ripe  and  hard. 

Diseases  and  enc?nies.  Wheat  is  subject  to  disease,  and  to  the 
attacks  of  insects,  which  are  frequent  causes  of  its  failure, 
and  which  render  it  in  many  places  an  uncertain  crop.  The 
principal  diseases  are  rust,  smut,  and  mildew  or  blight. 

1.  Rust  is  a  well  known  disorder,  in  which  the  straw  be- 
comes covered  over  with  a  red  powder  like  iron  rust.  This 
stops  the  growth,  and  renders  the  grain  shrivelled.  Rust 
takes  place  either  in  a  season  of  drought,  or  in  July  and  Au- 


DISEASES  AND  ENEMIES  OF  WHEAT.  329 

gust,  when  the  weather  is  damp  and  warm.  The  wheat  is 
thus  forced  to  such  a  rapid  growth  that  the  vessels  are  burst, 
and  the  sap  exudes  and  causes  the  rust.  In  either  case  there 
is  no  known  remedy. 

2.  Mildew  or  blight  gives  to  the  plant  a  purple  or  bluish 
cast,  resembling  the  mould  on  damp  walls  ;  and  is  supposed 
to  be  due  to  a  species  of  parasitic  plant,  a  fungus  which 
attaches  itself  to  the  stalk.  This  happens  during  warm,  wet 
weather,  or  heavy  dews.  The  only  remedy  is  to  brush  off  the 
water  in  the  morning  by  dredging  the  field  with  a  rope. 

3.  Smut  is  of  two  kinds.  The  first  kind  is  seen  in  the  heads, 
about  the  time  of  the  ripening  of  the  grain ;  the  heads  soon  dis- 
appear, leaving  nothing  but  the  naked  stalks.  The  second  kind 
appears  in  the  form  of  a  black  dust,  which  soon  spreads  itself 
over  the  field.  The  grain  is  not  destroyed,  but  the  flour  is 
rendered  black  and  poor.  This  is  also  supposed  to  be  a  spe- 
cies of  fungus,  as  it  can  be  propagated  through  a  field.  This 
disease  may  be  prevented  by  soaking  the  seed  in  strong  brine 
or  stale  urine,  sprinkling  it  while  wet  with  slacked  lime,  and 
leaving  it  for  twenty-four  hours  before  sowing. 

The  enemies  of  wheat  are  the  wire-worm,  Hessian  fly  and 
grain  insect. 

1.  Wire-worm.  This  worm  is  well  known  to  farmers,  and 
its  ravages  are  mostly  confined  to  the  sward.  This  effect 
may  be  remedied  by  ploughing  in  the  fall,  so  that  the  frosts 
of  winter  may  destroy  the  worm. 

2.  The  Hessian  fly  is  found  as  a  maggot  between  the  leaf 
and  the  culm,  in  the  first  joint  of  the  plant,  and,  by  bedding 
itself  in  the  stalk,  destroys  it.  No  certain  remedy,  for  the 
ravages  of  this  insect,  has  as  yet  been  found.  Late  sowing 
will  sometimes  carry  the  crop  beyond  the  fly-season. 

4.  The  grain  insect  appears  in  the  form  of  a  fly,  hovering; 
over  the  field  about  the  time  the  grain  is  in  blossom.  It  de^ 
posits  its  eggs,  from  which  a  yellow  maggot  is  hatched,  and 
appears  in  the  head  after  it  has  destroyed  the  grain.      A 

28 


330  PRACTICAL  AGRICULTURE. 

complete  preventive  against  this  insect  has  been  discovered, 
which  consists  simply  in  sprinkling,  at  the  flowering  season, 
slacked  lime  over  the  grain  while  wet.  Mr.  Colman  thinks 
that  this   may  generally  be  relied  on  as  a  certain  preventive. 

The  barberry  bush  has  been  thought  to  be  injurious  to 
wheat,  rye  and  barley,  by  causing  it  to  blast. 

Rye  is  the  seed  of  secale  cereale,  and  has  also  been  long 
cultivated  for  food.  In  the  north  of  Europe,  it  ranks  next 
to  wheat  for  bread,  and  is  used,  for  the  same  purpose,  in 
many  parts  of  this  country,  particularly  with  Indian  corn 
for  brown  bread,  a  very  healthy  and  cheap  article  of  diet. 
Rye  is  not  regarded  as  a  very  profitable  crop,  but  if  we  con- 
sider the  fact,  that  it  will  grow  on  sandy  plains,  Avith  little 
^(>r  no  manure,  and  yield  from  10  to  20  bushels  to  the  acre, 
we  must  regard  it  as  of  great  value;  for  it  is  the  only  grain 
which  will  grow  on  soils  containing  more  than  85  per  cent, 
of  sand. 

The  time  of  sowing  rye  is  in  August  or  September,  either 
after  potatoes  or  corn,  or  upon  a  summer  fallow.  The  quan- 
tity should  be  about  one  bushel  to  the  acre.  It  may  also  be 
sown  in  the  spring,  but  the  winter  rye  is  generally  the  most 
certain  and  productive  crop.  The  general  practice  of  our 
farmers  is,  to  plough  up  sandy  plains  once  in  three  years,  and 
take  a  crop  of  this  grain,  and  then  let  the  soil  rest  for  a  year 
or  two,  and  take  another  crop.  This  practice  cannot  be  too 
severely  censured.  If  clover  were  sown  with  the  rye,  on 
such  lands,  and  turned  in  with  the  stubble,  the  soil  would 
soon  become  enriched  and  fitted  to  bear  any  crop.  If  the 
clover  will  not  grow,  spread  on  ashes,  plaster  or  lime,  and  as 
soon  as  the  roots  become  fixed  in  the  soil,  there  is  not  the 
least  diflficulty  in  rendering  the  land  as  fertile  as  you  please. 
Instead  of  8  or  10  bushels  to  the  acre,  once  in  three  years, 
our  farmers  ought  to  raise,  at  least  25  bushels  with  root  crops 
and  corn  in  the  interval. 


CULTIVATION  OF  OATS. 


331 


The  expense  of  cultivating  rye,  and  the  average  product, 
may  be  stated  per  annum  as  follows. 


Ploughing, 
One  bushel  seed, 
Sowing  and  harrowing, 
Reaping, 
Threshing, 


2,00 
1,25 
1,00 
2,00 
2,00 


$8,25 
Rye  is  subject  to  a  disease  called  ergot 


Produce  on  an  average, 
15  bushels,  at  $  1,25 
Straw, 

Deduct  expenses, 

Net  firain,  <l! 


lft,75 
5,00 

23;75 

8,25 

$T5;50 

It  is  a  kind  of 
black  spur  in  the  head.  It  has  been  supposed  to  be  a  spe- 
cies of  fungus. 

Oats  {avena  sativa)  are  cultivated  as  an  article  of  food, 
both  for  man  and  beast.  They  will  grow  on  any  soil,  and 
are  generally  cultivated  after  corn  or  potatoes  without  ma- 
nure, although  some  prefer  to  sow  on  green  sward.  Three 
bushels  are  required  to  the  acre.  The  land  should  be  plough- 
ed once  and  thoroughly  harrowed.  Oats  are  a  very  sure 
crop,  and  may  be  estimated  at  40  bushels  to  the  acre  upon 
an  average.  In  consequence  of  their  demand  at  livery  sta- 
bles, they  usually  bring  a  price  above  their   intrinsic  value. 

The  expenses  of  cultivation,  and  the  returns,  are  generally 
as  follows. 


Seed,  3  bush,  at  50  cts.. 
Cradling  and  harvesting, 
Threshing, 


2,00 
1,50 
2,00 
3,00 

$8,50 


Produce  on  an  average, 

40  bush,  at  50  cts., 
Straw, 

$ 
Deduct  expenses, 

Net  gain. 


20,00 
10,00 

'3o;oo 

8,50 
21,50 


It  will  be  seen,  that  this  is  a  very  profitable  crop,  especial- 
ly as  oats  bring  ready  money,  in  almost  any  market.  But 
if  proper  pains  are  taken,  and  the  land  properly  prepared, 
crops  of  60  bushels  may  be  obtained.  Governor  Da- 
vis of  Worcester,  Mass.  has  raised  100  bushels  to  the  acre. 
It  should  be  remarked  here,  that  there  are  two  principal  va- 
rieties ;  the  common  oat,  with  a  spreading  top,  and  the  Tar- 
tarian, or  horse-mane  oat,  so  called,  because  the  seed  hangs 
in  clusters  on  one  side.     As  the  two  varieties  ripen  at  differ- 


332  PRACTICAL  AGRICULTURE. 

ent  times,  they  should  not  be  sowed  together.  The  produce 
is  equal  in  both  varieties,  but  the  Tartarian  has  a  shorter 
stratv. 

Barley  (hordeum  vulgare)  is  extensively  cultivated,  partly 
as  an  article  of  food,  and  partly  for  malt  liquors  and  ardent 
spirits.  The  summer  barley  is  the  only  variety  cultivated  in 
the  United  States. 

Barley  seed,  before  sowing,  should  be  steeped  twenty-four 
hours  in  soft  water,  in  order  to  promote  the  germination  of 
all  the  grain  and  its  ripening  at  the  same  time. 

The  soil  should  be  rich  and  mellow,  although  it  will  flour- 
ish tolerably  on  a  clay  soil,  free  from  weeds.  Crops  of  tur- 
nips or  potatoes  are  the  best  preparation  for  this  crop.  The 
seed  should  always  be  sowed  upon  a  fresh-stirred  soil,  as 
early  as  the  land  will  allow  in  the  spring,  and  from  2  to  3 
bushels  should  be  allowed  to  the  acre.  The  barley  may  be 
i^radled  in  the  same  manner  as  oats.  The  value  of  this  crop 
may  be  thus  estimated  per  acre. 

Produce,  30  bush,  at  80  cts. 


Ploughing,  2,00 

Seed,  3  bush,  at  80  cts.  2,40 

Sowing  and  harrowing,  1 ,50 

Harvesting,  2,50 

Threshing,  2,80 

$11,20 


per  bushel,  24,00 

Straw,  5,00 

2;',00 

Deduct  expense,  11,20 

$  17,80 


This  is  probably  about  an  average  for  this  crop,  yet  fifty- 
four,  and  even  sixty  bushels  have  been  produced  on  a  single 
acre.  When  clover  and  grass  seeds  are  sown  with  it,  it  is 
recommended  to  delay  the  sowing  of  the  grass  seed,  until 
the  barley  has  just  appeared  above  the  soil  and  then  harrow 
it  in.  This  will  effect  the  barley  favorably,  and  increase 
the*quantity  of  both  crops. 

Buckwheat  is  a  valuable  crop,  because  it  will  flourish  well 
on  a  sandy,  poor  soil.  It  is,  however,  but  little  cultivated  in 
New  England.  It  is  one  of  the  best  crops  for  turning  in  to 
the  soil  to  increase  the  quantity  of  vegetable  matter.  It  will 
yield,  upon  an  average,  30  bushels  per  acre,  and  the  flour  is 


CULTIVATION  OF  ROOTS.  iRlp 

much  esteemed  for  making  warm  cakes,  and  brings  as  high 
a  price  as  wheat.  It  is  easily  cultivated,  and  may  be  sown 
as  late  as  July,  but  the  flour  is  not  always  good. 

Flax  and  hemp  are  cultivated  to  a  very  limited  extent  in 
this  country.  For  a  particular  description  of  their  mode  of 
culture,  the  reader  is  referred  to  the  agricultural  publications 
of  the  day. 

Rice  and  cotton  are  also  cultivated  in  the  South,  but  the 
methods  of  culture  need  no  description  in  this  connection. 

Sect.  2.  Cultivation  of  Roots. 

The  cultivated  roots  are  the  beet,  carrot,  turnip,  potato, 
parsnip,  onion,  etc.  From  their  influence  upon  the  soil,  and 
the  small  quantities  of  alkalies  they  extract,  they  are  gene- 
rally considered  ameliorating  crops.  As  many  of  them  are 
provided  with  broad  leaves,  they  extract  most  of  their  nour- 
ishment from  the  atmosphere  and  from  water. 

Potato.  The  potato  is  the  bulb  of  the  solanum  tubero- 
sum, and  grows  wild  in  the  mountainous  districts  of  Peru 
and  Chili.  Potatoes  are  in  almost  universal  use,  and  the  most 
valuable  of  root  crops.  In  the  course  of  cultivation,  several 
varieties  have  been  produced  by  a  treatment  similar  to  that 
pursued  with  corn.  It  is  not  consistent  with  our  limits,  to 
treat  of  the  different  varieties  and  their  comparative  merits. 
The  English  white,  the  blue,  red,  kidney,  rohan,  lady's-fin- 
ger,  long-red  and  chenango  are  names  by  which  several  va- 
rieties are  designated.  As  the  potato  is  generally  propagated 
by  eyes  or  the  tubers,  and  not  by  the  seeds,  it  has  been  a 
question  much  discussed  by  farmers,  whether  the  whole  po- 
tato should  be  planted,  or  only  the  cuttings.  This  question 
has  been  very  satisfactorily  settled  by  experiment.  It  is 
found  that  the  seed  end,  or  that  opposite  to  the  stalk,  cut 
rather  deep,  yields  the  largest  and  most  thrifty  shoots  and  the 
most  bountiful  crop.* 

*  See  experiments  in  Buel's  Cultivator,  Vol.  III.  p.  182. 

28* 


334  PRACTICAL  AGRICULTURE. 

The  seed  end  is  always  to  be  prefered  for  several  reasons. 
1.  The  potatoes  will  be  two  weeks  earlier.  2.  The  other 
part  of  the  potato  is  valuable  for  cooking  or  domestic  ani- 
mals. 3.  The  eyes  next  to  the  point  where  the  tuber  is  at- 
tached to  the  stalk,  will  produce  only  weak  shoots  and  small 
tubers.  Hence,  as  the  size  of  the  tuber  will  depend  upon 
the  seed,  and  size  of  the  tuber  from  which  the  seed  is  taken, 
we  have  an  easy  and  certain  rule  which  we  may  adopt,  in 
reference  to  the  seed  required  for  this  crop.  The  quantity  of 
seed  may  vary  from  10  to  20  bushels  per  acre. 

The  soil  best  fitted  for  potatoes,  is  a  light  sandy  loam ;  but 
they  will  flourish  well  on  almost  any  soil,  especially  on  green 
sward.  For  culinary  purposes,  the  soil  should  be  light  and 
dry,  but  of  a  deep  tillage. 

The  mode  of  preparing  the  soil,  is,  either  to  turn  it  over 
after  green  manure  or  compost  has  been  spread  over  the  sur- 
face, or,  if  moist,  to  throw  it  into  ridges,  and  plant  the  pota- 
toes in  drills  or  rows,  about  six  inches  apart.  In  the  former 
case,  the  potatoe  hills  may  be  3  feet  by  2,  with  3  or  4  seed 
ends  in  a  hill.  Whether  potatoes  should  be  cultivated  in  hills 
or  drills,  is  not  well  settled.  It  is  a  common  practice  to  ma- 
nure potatoes  in  the  hills  or  drills,  but  unless  there  is  a  want 
of  manure,  this  process  is  not  so  good  as  that  of  burying  the 
manure  deeply  under  the  surface.  Potatoes  require  to  be 
covered  from  3  to  6  inches  in  depth,  according  to  the  mois- 
ture of  the  soil.  The  after  culture  should  be  first  with  the 
cultivator,  and  then  with  the  hoe.  Some  recommend  a  flat 
surface,  which  may  succeed  well,  if  the  soil  is  very  deep  and 
light ;  otherwise,  there  should  be  large  broad  hills,  in  order 
to  give  the  air  and  water  a  free  circulation  to  the  roots. 

The  time  of  harvesting  potatoes  will  depend  upon  their 
maturity.  They  should  be  suffered  to  remain  in  the  ground 
until  the  stalk  is  perfectly  dry.  If  the  tubers  are  taken  qut  of 
the  ground  before  they  are  perfectly  ripe,  they  will  be  liable 
to  wilt,  or  to  become  unwholesome  before  spring.     The  best 


ROOT  CROPS BEETS.  335 

mode  of  securing  them,  is  to  put  them  in  pits,  into  which  but 
a  small  quantity  of  air  is  admitted.  When  left  in  the  ground, 
they  are  much  better  in  the  spring  than  when  exposed  to  the 
air  in  cellars.  Daubeny  states,  that  they  may  be  preserved 
perfectly,  by  freezing  them  up  solid  in  the  fall,  and  thawing 
them  in  the  spring  and  rapidly  drying  them. 

The  following  is  an  estimate  of  the  value  of  this  crop  in 
Massachusetts.  Ploughing  §4,00  per  acre ;  manuring  in  hill 
$15,00  ;  seed,  20  bushels,  worth  $5,00  ;  two  hoeings,  $4,00, 
and  digging,  $10,00 ;  amounting  in  all  to  $38,00.  The  aver- 
age produce  is  200  bushels  to  the  acre,  worth  at  least  $50,00. 
This  would  give  a  net  profit  of  $12,00  per  acre.  In  some 
places,  the  value  of  the  crop  is  more  than  double  this  sum  ;  in 
others,  less  than  half  of  it.  But  $12,00  per  acre  may  be  re- 
garded as  an  average  profit  on  every  acre  of  potatoes  culti- 
vated in  the  State. 

Beets.  There  are  several  varieties  of  this  root  ;  four  vari- 
ties,  at  least,  are  cultivated  to  some  extent  in  this  country. 

1.  Mangel  Wurtzel.  This  is  the  largest,  and  most  pro- 
ductive of  the  family. 

Fig.  20- 


The  soil  required  for  this  crop,  is  a  deep,  moist,  clayey 
loam.  The  tillage,  as  in  all  cases  with  root  crops,  should  be 
deep ;  and  the  sub-soil  plough  used,  to  render  the  earth  per- 
meable by  the  roots,  to  the  depth  of  12  or  16  inches.  The 
seeds  may  be  sown  with  a  drill-barrow,  (Fig.  20),  and  covered 
with  a  hoe  in  rows  about  2  feet  apart,  or  they  may  be  dropped 


336  PRACTICAL  AGRICULTURE. 

by  means  of  a  dibble.  This  instrument  is  made  of  wood,  with 
a  handle  3  feet  long,  a  head  like  a  rake,  and  from  6  to  12  teeth 
one  inch  in  diameter  ;  it  is  made  so  that  it  may  be  stamped 
down,  and  the  holes  made  an  inch  or  two  deep,  about  2  inches 
apart.  A  boy  may  then  follow,  and  drop  one  seed  into  each 
hole  and  cover  with  fine  mould  half  an  inch  deep.  They 
should  be  sown  the  last  of  May.  The  after-culture  consists 
simply  in  keeping  the  ground  clear  of  weeds,  and  of  thinning 
the  plants  to  the  distance  of  8  or  10  inches.  The  roots 
should  be  gathered  as  soon  as  they  are  ripe ;  which  may  be 
known  by  the  under  leaves  becoming  yellow.  They  may 
be  preserved  in  cellars,  and  fed  out  to  farm  stock. 

The  cost  of  cultivating  this  crop,  is  estimated  at  about 
f  30,00  per  acre ;  and  they  yield,  at  least  600  bushels,  which, 
allowing  a  fair  price  for  them,  would  leave,  at  least  $25,00 
net  profit  per  acre. 

2.  The  turnip  and  blood  beet  are  cultivated  in  gardens,  and 
to  some  extent  in  fields.  They  are  best  cultivated  in  ridges; 
that  is,  by  throwing  two  furrows  together,  and  sowing  the 
seed  in  double  rows  as  above. 

3.  The  sugar  beet,  or  white  variety,  is  cultivated  on  a  lim- 
ited scale  in  this  country,  but  it  supplies  France  with  nearly 
all  her  sugar. 

This  beet  is  a  very  profitable  crop,  and  is  beginning  to  be 
introduced  into  this  country.  In  1841,  Mr.  Tudor,  of  Na- 
hant,  raised  a  crop  which  yielded  at  the  rate  of  more  than  36 
tons  to  the  acre,  or  about  1,300  bushels.  The  value  of  this 
crop  must  be  equal  to  $180,00  ;  which  is  sufficient  to  pay  all 
the  expense  of  cultivation,  and  leave  a  large  profit.  It  should 
be  remarked,  however,  that  the  soil  was  put  in  the  best  possi- 
ble condition,  and  in  all  cases,  deep  tillage  is  essential  to  suc- 
cess. The  juice  of  this  beet  is  boiled  into  sugar,  which 
equals  that  made  from  sugar  cane.  But  the  chief  value  of 
this  variety  in  this  country,  is  to  feed  out  to  farm  stock. 

Carrots  are  beginning  to  be  cultivated  for  farm  stock ; 


ROOT  CROPS PARSNBP.  337 

theif  mode  of  culture,  is  in  all  respects  similar  to  that  of  beets  ; 
they  require  a  similar  soil,  and  the  same  attention  to  ensure  a 
crop.  The  value  of  carrots  for  field  culture,  is  fully  equal  to 
that  of  beets.  They  will  yield  about  the  same  quantity  of 
food,  and,  for  horses,  are  decidedly  preferable  to  beets  or  any 
other  roots. 

The  value  of  this  crop  is  also  beginning  to  be  estimated, 
by  many  of  our  farmers.  We  do  not  see  why  this  root  is  not 
cultivated  instead  of  the  Swedish  turnip,  as  we  believe  that 
it  is  much  more  valuable  for  farm  stock,  especially  for  cows 
which  give  milk. 

Parsnip.  The  parsnip  is  also  beginning  to  be  cultivated 
for  farm  stock,  and  requires  the  same  treatment  as  beets  and 
carrots.  Parsnips  are  equally  productive,  and  much  better 
for  some  purposes.  They  may  remain  in  the  ground  over 
winter,  and  be  fed  out  in  the  spring.  On  this  account,  they 
are  preferable  for  feeding  stock  late  in  the  season.  We  do 
not  know  why  this  root  is  not  cultivated  more  extensively  by 
all  our  farmers. 

Artichoke.  The  Jerusalem  artichoke  is  a  root  which  is 
valuable  for  light  sandy  soils.  The  introduction  of  it  among 
the  cultivated  roots,  would  be  of  the  greatest  advantage  to  ag- 
riculture. (See  p.  129.) 

Onion.  This  can  hardly  be  regarded  as  a  field  crop,  al- 
though they  are  raised  in  great  abundance  near  our  cities. 
Their  mode  of  culture  is  well  known.  They  require  a  moist 
soil,  and  may  be  cultivated  several  years  in  succession  on 
the  same  field. 

Turnips.  The  introduction  of  the  turnip  among  the  cul- 
tivated crops,  constitutes  an  era  in  the  art  of  husbandry. 
Of  the  several  varieties  which  are  cultivated,  we  may  select 
three,  as  most  worthy  of  attention :  the  yellow,  white  and 
Swedish  or  ruta  baga  turnips. 

1.  Ruta  baga  or  Swedish  turnip  is  the  most  important  of 
these  varieties,  and  yields  the  largest  quantity  of  vegetable 


338  PRACTICAL  AGRICULTURE. 

matter  for  the  use  of  farm  stock.  It  should  be  remarked,  al- 
so, that  there  are  varieties  in  this  root.  The  best  have  a  yel- 
lowish look,  globular  form,  and  have  no  neck  or  stem.  The 
green  and  yellow  kinds  often  prove  abortive.  The  seed 
should  be  black  and  full.  One  pound  will  suffice  for  an 
acre  of  land.  One  half  a  pound  will  produce  plants  enough 
for  an  acre ;  but  as  the  seed  is  liable  to  fail,  a  pound  is  not 
too  much  to  ensure  a  crop. 

The  time  for  sowing  is  from  the  20th  of  June  to  the  5th  of 
July. 

The  soil  best  adapted  to  turnips,  is  a  light,  dry  and 
friable  loam  ;  or  almost  any  dry  soil,  with  the  exception  of 
heavy  clays. 

The  soil  is  best  prepared  by  throwing  it  into  drills  8  feet 
apart,  filling  the  drills  with  short  manure  or  compost,  and  af- 
ter covering  it  with  a  plough,  two  furrows  on  each  side,  sow 
with  a  drill-barrow,  p.  335.  The  ruta  baga  flourishes  best 
on  a  clover  ley,  and  may  be  sowed  after  the  first  crop  of  clo- 
ver is  taken.  If  long  manure  is  applied,  it  should  be  covered 
with  a  plough.  If  rotted,  it  should  be  placed  under  the  seed, 
so  that  the  roots  will  penetrate  it.  The  plants  generally 
make  their  appearance  in  8  or  10  days  after  sowing ;  they 
should  then  be  horse-hoed  with  the  cultivator,  and  the  soil 
should  be  removed  as  near  to  the  plants  as  possible,  in  order 
to  destroy  the  weeds.  The  hoe  should  then  be  employed, 
and  the  plants  thinned  to  a  distance  of  8  or  10  inches. 

The  quality  of  this  crop  depends  upon  the  size  ;  and  what 
is  rather  remarkable,  the  larger  they  are  the  more  nutriment 
they  possess  in  proportion  to  their  weight. 

Gathering.  The  roots  may  be  easily  drawn  with  the  hand. 
The  tops  and  tap-roots  should  be  cut  off,  and  they  should  be 
permitted  to  dry  on  the  ground,  until  the  dirt  may  be  sepa- 
rated from  them.  They  should  then  be  stored  in  pits,  3  feet 
in  breadth,  and  covered  with  a  good  thickness  of  earth.  The 
value  of  this  crop  is  variously  estimated  by  different  farmers. 


ROOT  CROPS TURNIPS.  339 

The  products  are,  upon  an  average,  600  bushels  per  acre. 
Some  estimate  the  net  profit  at  80  dollars  per  acre  ;  but  their 
value  will  vary  in  different  places  and  seasons.  There  is  no 
doubt  but  that  it  is  one  of  the  most  valuable  crops  raised  by 
the  farmer,  although  they  are  much  less  esteemed  than  they 
formerly  were. 

Use.  This  root  is  excellent  for  all  kinds  of  farm  stock. 
They  are  said  to  be  useful  for  fattening  hogs,  cattle  and  sheep. 
They  may  be  fed  raw,  sliced,  and  a  small  quantity  of  salt 
sprinkled  over  them. 

2.  The  wliite  turnip  requires  a  similar  soil  and  treatment ; 
but  may  be  sowed  as  late  as  the  2.5th  of  July.  They  are  not 
so  productive  as  the  preceding,  but  are  excellent  for  a  second 
crop,  or  for  feeding  cattle  in  the  fall ;  by  which  course  light 
soils  may  be  improved. 

3.  The  yellow  varieties  may  be  sown  about  the  1.5th  of  July, 
and  are  richer  than  the  white.  Sinclair  estimates  the  amount 
of  nourishment  in  64  drachms  as  follows. 


White  tankard 

76grs. 

Store  or  garden 

85  grs 

Common  white  loaf 

80   " 

Ruta  baga 

110    « 

Norfolk  white 

73  " 

The  following  table  gives  the  nutritive  properties  of  several 
varieties.     The  green-top  yellows  being  taken  as  a  standard. 


Species  and  Varieties.            Siiouid  weigh 

by  Size  &  Standard. 

Actual  Weight 

Ihs.  oz. 

lbs.  oz. 

Green-top  yellow 

16.00 

15.00 

Swedish  or  ruta  baga 

11.2 

13.12 

Red-top  yellow 

12.00 

12.10 

Dalis  hybrid 

13.12 

12.00 

White  globe 

20.8 

15.8 

Red-top  white 

16.8 

13.00 

Green-top  white 

8.7 

8.8 

White  tankard 

16. 

14. 

Purple     do. 

12.10 

11.8 

This  table  shows  the  superiority  of  the  ruta  baga  -over  all 
the  other  varieties.  It  yields  about  6  or  7  per  cent,  of  its 
whole  weight  of  nutritive  matter,  while  the  white  varieties 


340  PRACTICAL  AGRICULTURE. 

afford  4  per  cent.,  and  in  the  largest  roots  only  3 J  per  cent, 
of  their  whole  weight ;  hence,  one  acre  of  the  Swedish  varie- 
ty is  equal  to  one  and  a  half  acres  of  the  white.  "  No  per- 
son," says  Lord  Kaimes,  "  ever  deserved  better  of  his  coun- 
try, than  he  who  first  cultivated  turnips  in  a  field.  No  plant 
contributes  more  to  fertility." 

It  appears  from  the  investigations  thus  far  made,  that  roots 
are  by  far  the  most  profitable  crops  cultivated  by  the  farmer ; 
and  that  their  more  general  introduction  would  both  increase 
the  value  of  the  soil,  and  the  quantity  of  productions  from 
the  farm,  from  the  dairy  and  from  farm  stock. 

Sect.  3.     Cultivation  of  Grasses. 

Grasses  constitute  the  principal  food  of  farm  stock,  and, 
reciprocally,  the  food  of  future  crops ;  hence,  their  cultiva- 
tion must  be  an  important  branch  of  agriculture  in  almost 
every  country,  but  especially  in  countries  in  which  from  4  to 
6  months  of  the  year,  the  earth  is  destitute  of  herbage  ;  as  it 
is  in  most  temperate  and  cold  climates.  The  points  to  which 
the  farmer  should  direct  his  attention  in  the  cultivation  of  the 
grasses,  are  the  selection  of  seed,  and  soil  adapted  to  the 
character  of  the  plant;  the  preparation  of  the  soil ;  the  sow- 
ing of  the  seed ;  the  time  and  mode  of  securing  the  crop,  and 
its  comparative  value.  The  cultivated  grasses  may  include 
what  have  been  called  herbage  plants,  of  which  the  clovers  and 
lucern  are  the  only  kinds*  which  have  been  cultivated  in  this 
country. 

I.  Clovers.  There  are  three  species  of  clover,  usually  cul- 
tivated by  the  farmers  of  this  country,  and  two  other  species, 
which  have  been  cultivated  in  Great  Britain,  in  which  coun- 
try clovers  were  first  cultivated  in  the  16th  century. 

*  Sanfoin,  bird's-foot,  trefoil,  parsley,  burret,  rib-wort,  plantain, 
broom,  wild-flower,  yarrow,  etc.  are  of  this  class  ;  but  are  of  little  im- 
portance, with  the  exception  of  sanfoin,  which  requires  a  chalky  soil. 
The  bird's-foot  and  trefoil  have  been  but  partially  cultivated  among  us. 


CULTIVATION  OF  CLOVER.  341 

1.  Red  clover  {trifolium  pratense)  is  a  well  known  bien- 
nial, and  sometimes,  if  not  permitted  to  seed,  a  triennial  plant. 
It  does  not  mature  its  seeds  well  in  the  first  of  the  season, 
and  hence  it  must  be  fed  until  June,  or  else  the  seed  must  be 
obtained  from  a  second  crop,  which  will  ripen  in  August,  or 
the  first  of  September. 

T'he  soil  best  adapted  to  red  clover  is  a  deep  sandy  loam. 
The  long  tap-roots  will  extend  downward  to  a  great  depth  ; 
and  hence  deep  dry  soils,  of  almost  any  description,  are  well 
suited  to  it,  although  it  prefers  one  in  which  there  is  a  large 
quantity  of  lime. 

The  quantity/  of  seed  depends  upon  the  soil ;  it  is  usually, 
in  this  country,  10 lbs.  to  the  acre;  in  Flanders,  6 lbs. ;  and, 
in  Great  Britain,  14.  The  greater  the  number  of  plants  which 
can  be  made  to  grow,  the  finer  and  better  the  quality  of  the 
hay. 

The  time  of  sowing  clover  seed  is  in  the  spring,  either  with 
a  grain  crop,  and  before  the  last  harrowing  or  bushing,  or 
upon  winter  grain,  just  as  the  snows  are  leaving,  in  March  or 
April.  The  sowing  should  be  followed  by  a  light  harrow  or 
roller.  The  latter  especially  will  be  of  essential  service  to 
the  grain  crop.  If  the  soil  is  wet,  or  a  stiff  clay,  the  seed 
should  be  sown  in  mid-summer  with  buckwheat.  The  prac- 
tice of  sowing  clover  seeds  in  the  autumn,  should  be  discon- 
tinued, as  the  plant  rarely  attains  sufficient  strength  to  sur- 
vive the  frosts  of  winter. 

During  the  growth  of  clover,  the  crop  may  be  much  in- 
creased by  sprinkling  the  surface  of  the  young  shoots,  in  the 
spring,  with  plaster,  one  bushel  to  the  acre  ;  and  if  the  crop 
is  continued  for  several  years,  a  top  dressing  of  lime  or  ashes 
will  prove  highly  beneficial. 

The  time  of  cutting  clover,  when  intended  for  hay,  is  at  a 

period  when  it  is  in  full  bloom.     It  is  then  much  lighter,  but 

the  stalks  are  more  tender,  and  will  fatten  stock  much  faster, 

than  if  permitted  to  remain  until  the  seeds  ripen.     And  fur- 

29 


342  PRACTICAL  AGRICULTURE. 

ther,  two  crops  may  be  cut  the  same  season,  one  for  hay  and 
the  other  for  seed,  or  both  for  hay. 

The  methods  of  making  clover  into  hay  are  variously  de- 
scribed by  different  practical  farmers.  The  following  seems 
to  accord  best,  both  with  theory  and  the  experience  of  the 
best  farmers.  After  the  swaths  are  turned,  they  should  be 
spread  just  so  that  the  heat  of  the  sun  will  wilt  and  partially 
dry  the  leaves  ;  the  clover  may  then  be  placed  in  grass-cocks, 
about  6  feet  high,  using  a  fork  instead  of  a  rake.  By  this 
means  the  cocks  may  be  formed  with  the  straws  all  inclining 
downward,  so  as  to  carry  off  the  rain.  The  rake  may  then 
pass  over  the  ground  to  gather  up  the  remainder.  The  cocks 
should  always  be  formed  before  the  leaves  begin  to  crumble, 
and  before  the  dew  begins  to  fall.  The  cocks  may  now  stand 
from  36  to  48  hours,  until  they  grow  quite  warm.  They 
should  be  opened  after  the  dew  is  off,  spread  out  G  inches 
thick,  turned  between  12  and  2,  and,  if  the  day  is  good, 
gathered  into  the  barn  one  or  two  hours  afterwards.  A  small 
quantity  of  salt,  3  or  4  quarts  to  a  load,  should  be  mingled  in 
the  mow. 

The  advantages  of  this  course  have  been  tested  by  the 
experience  of  the  best  farmers.  The  reasons  for  it  are  found 
in  the  size  of  the  stalk  compared  with  the  leaf.  When  spread, 
and  exposed  to  a  hot  sun,  the  leaves  dry  up  to  a  crisp,  and 
fall  off  before  the  stalks  are  sufficiently  dried  to  be  placed  in 
the  mow,  without  the  danger  of  heating.  In  the  cock,  the 
heating  process  commences,  and  all  parts  of  the  plant  are 
dried  alike ;  if  fermentation  is  arrested  at  the  proper  time,  it 
will  not  be  so  liable  to  heat  in  the  mow,  and  hence  will  con- 
tinue green,  fresh  and  sweet  until  used. 

2.  The  C020  grass  or  southern  clover  {trifolium  medium 
or  trifolium  Pcnnsylvanicum)  is  a  perennial,  resembling  the 
red  clover,  but  shorter  and  with  paler  flowers.  It  is  a  fort- 
night earlier  than  the  preceding.  Hence  two  crops  may  be 
cut  the  same  season,  even  if  fed  until  the  20th  of  June;  or  if 


i 


CULTIVATION  OF  LUCERNE.  343 

the  first  crop  is  taken  by  the  28th,  the  second  crop  will  mature 
its  seeds. 

3.  White  clover  {trifolium  repens)  is  also  a  perennial  and 
a  very  sweet  and  useful  plant ;  it  should  be  sown  more  fre- 
quently than  it  is.  It  is  mostly  found  in  pastures  and  furnishes 
the  best  of  food  for  grazing.  The  yellow  and  scarlet  clover 
are  not  cultivated  among  us,  though  the  former  is  in  England. 
Clover  is  admirably  adapted  to  an  alternating  system  of  hus- 
bandry, as  two  crops  may  be  cut  in  one  season.  As  its  roots 
penetrate  and  divide  the  soil  and  exhaust  but  little  from  it, 
we  are  astonished  that  our  farmers  do  not  cultivate  it  more, 
and  are  disposed  to  subscribe  fully  to  the  sentiment  of  the 
Flemmings,  that  "no  man  in  Flanders  would  pretend  to  call 
himself  a  farmer  without  clover." 

4.  Lucerne  {incdicago  sativa)  is  called  in  this  country, 
French  clover.  It  is  a  perennial  plant,  sending  up  several 
small  shoots  resembling  clover,  but  with  spikes  of  blue  or 
violet  flowers.  It  was  early  cultivated  by  the  Romans,  and 
is  now  cultivated  in  many  countries  of  Europe,  South  Ameri- 
ca and  the  United  States.  The  seed  of  lucerne  is  obtained 
in  the  same  manner  as  that  of  red  clover,  from  the  second 
crop,  and  is  contained  in  pods  which  are  easily  threshed. 

The  soil  should  be  siliceous,  with  deep  tillage  and  dry 
sub-soil.  No  soil  is  too  rich  for  it,  and  unless  it  is  well  pre- 
pared by  finely  pulverizing  it,  the  crop  is  liable  to  fail. 
Loudon  recommends  trenching,  but  it  flourishes  well  after 
potatoes  or  roots  of  any  kind,  provided  the  manures  are  green 
and  deeply  ploughed  in. 

The  time  for  solving  varies  from  the  1st  to  the  20th  of  May, 
and  the  quantity  of  seed  is  from  15  to  20  lbs.  per  acre  when 
sowed  broad-cast  with  rye,  and  10  lbs,  when  sown  in  drills, 
three  feet  apart,  and  other  crops  (as  roots)  cultivated  between. 

The  after  culture  of  this  crop  consists  in  harrowing,  twice 
a  year,  after  the  first  year  (if  sown  broad-cast),  and  in  remov- 
ing all  the  weeds.     But  if  sowed  in  drills,  it  must  be  culti- 


344  PRACTICAL  AGRICULTURE. 

vated  with  the  cultivator  and  kept  clear  of  weeds.     Ashes, 
gypsum  and  lime  are  excellent  top  dressings. 

The  time  of  cutting  and  the  mode  of  curing,  are  precisely 
the  same  as  for  clover,  but  it  is  fed  to  the  best  advantage  in  a 
green  state,  or  for  the  purpose  o^  soiling,  see  p.  64.  It  may 
be  cut  for  this  purpose  from  three  to  five  times  in  a  single 
season,  and  the  quantity  cut  from  one  acre,  has  been  stated  at 
from  5  to  8  tons,  in  one  season.  The  soiling  of  one  acre  is 
sufficient  to  keep  from  5  to  6  cows  during  the  soiling  season. 
It  is  therefore  an  invaluable  plant,  where  pasturage  is  scarce 
or  dear.  But  it  is  also  an  excellent  hay,  equal  in  all  re- 
spects, according  to  some  farmers,  to  clover. 

5.  Timothy  (phleum  pratense)  is  better  known  in  this 
country  as  herdsgrass,  and  in  Europe,  as  meadoio  cats-tail. 
It  is  a  hardy,  perennial  plant,  growing  with  great  luxuriance 
in  our  climate  and  soil.  It  is  the  principal  foraging  grass  of 
the  Northern  States. 

The  seed  may  be  obtained  by  reaping  the  tops  down  from 
10  to  12  inches  and  cutting  the  remainder  for  hay. 

This  grass  flourishes  in  almost  any  soil,  capable  of  cultiva- 
tion, but  as  the  seeds  are  small,  particular  care  should  be 
taken  to  pulverize  the  soil,  and  to  cover  the  seed  lightly  with 
a  bush-harrow  or  with  the  roller. 

The  time  of  sowing  the  seed  may  be,  either  in  the  spring, 
with  the  spring  grain,  in  the  fiill  with  winter  rye,  or  just  be- 
fore the  ground  thaws  in  the  spring.  It  is  often  sown  with 
clover,  a  very  improper  practice,  because  the  clover  is  ripe 
at  least  two  weeks  earlier  than  the  timothy.  The  quantity 
may  be  from  4  to  5  lbs.  to  the  acre,  sown  broad-cast. 

Timothy  may  he  cured,  by  spreading  and  cocking  over 
night,  and  should  not  be  cut  till  its  seeds  are  formed,  hence 
it  exhausts  the  soil  more  than  the  clover.  But  the  value  of 
this  grass  is  increased  by  allowing  it  to  remain  on  the  ground 
until  the  the  seeds  are  in  the  milk ;  still,  if  it  is  cut  green, 
there  is  a  compensation  in  a  greater  amount  of  the  after-crop, 


RED  TOP ORCHARD  GRASS. 


345 


which  had  better  be  fed  on  the  ground,  than  removed  as 
rowin, 

6.  Redtop  {Agrostis  vulgaris)  is  the  herdsgrass  of  the 
Middle  and  Southern  States.  It  is  indigenous  to  the  soil, 
perennial,  and  well  adapted,  both  for  pastures  and  meadows, 
and  especially  for  reclaiming  swamps  and  wet  or  moist  lands. 
It  springs  up  spontaneously,  but  may  be  sown  with  timothy, 
and  in  the  same  way ;  and,  as  they  are  ready  to  be  cut  at  the 
same  season,  they  furnish  the  most  valuable  hay.  The  white- 
top,  or  fowlmeadow,  is  said  to  be  a  variety  of  this  species. 

7.  American  cock's-foot  or  orchard-grass  i^Dactylis  glo- 
merata)  is  one  of  the  most  permanent  grasses.  It  is  rather 
coarse  and  whitish  in  appearance,  with  broad  leaves,  and 
seed  glumes  resembling  a  cock's  foot,  from  which  it  receives 
its  name. 

This  plant  abounds  in  seeds,  but  they  are  very  light,  so 
that  two  bushels  are  sown  on  an  acre. 

The  best  time  and  mode  of  sowing  it,  is  with  clover,  be- 
cause its  growth  is  early  and  rapid,  and  both  are  fit  for  the 
scythe  at  the  same  time.  It  may  be  cultivated  and  cured 
in  all  respects  as  clover.  But  it  appears  best  fitted  to  pas- 
turage, both  because  of  its  rapid  growth,  and  because  it  is 
liable  to  grow  coarse  and  harsh.  Its  highest  value  is  obtain- 
ed by  keeping  it  cropped  closely  with  sheep,  but  when  cut 
early  with  clover,  the  after  growth  is  very  abundant  and  of 
great  value;  \  of  its  value  is  diminished  if  permitted  to  ripen 
its  seeds. 

8.  Tall  oat-grass  (^yc?m  eZafzor)  is  placed  by  Mr.  Taylor 
and  Mr.  Muhlenburgh  at  the  "  head  of  good  grasses."  The 
latter  says,  "  it  is  the  best  of  grasses,  and  the  earliest  for 
green  fodder  and  hay." 

The  seed  is  liable  to  waste  if  not  collected  in  season.     It 

may  be  sown  with  grain  crops  in  the  spring,  six  pecks  to  the 

acre,  according  to  Sinclair,  on  a  strong  tenacious  clay.     But 

a  clover  soil  is  well  adapted  to  it.     It  appears  to  be  better 

29* 


346  PRACTICAL  AGRICULTURE. 

adapted  for  pasture  than  for  meadows.     See  Complete  Farm- 
er, p.  228. 

9.  Sweet-scented  vernal  grass,  [Anthoxanthujn  odoratuni), 
and  meadow  foxtail  (Alopecurus  pratensis),  are  foreign 
grasses.  The  former  is  rather  scanty  of  herbage,  and  is 
used  for  cow  pastures ;  and  the  latter,  being  much  more 
abundant  in  produce  and  nourishment,  is  cultivated  in  Eng- 
land ;  but  both  have  been  introduced  into  the  neighborhood 
of  Boston  and  Philadelphia,  and  have  now  become  a  part  of 
the  ordinary  herbage  of  our  meadows. 

10.  Ryegrass  [Lolium perenne)  is  cultivated  in  Scotland, 
and  the  north  of  England;  "and  forms  the  principal  seed  sown 
with  clover."  There  are  several  varieties  of  this  grass,  but 
it  has  not  as  yet  flourished  well  in  our  climate.  It  requires 
a  moist  atmosphere,  and  is  not  considered  worth  cultivation, 
unless  in  elevated  and  moist  places.  Our  best  farmers  in 
New  England,  prefer  to  sow  all  grass  seeds,  with  the  excep- 
tion of  clover,  as  early  as  possible,  after  the  crop  in  Septem- 
ber, and  after  tlie  land  is  ploughed.* 

The  above  are  our  principal  grasses,  but  the  common  her- 
bage of  our  meadows  consists  of  several  other  varieties.  Sev- 
eral species  also  are  cultivated  in  other  countries,  but  are  not 
of  sufficient  importance  to  need  further  notice  in  this  connec- 
tion. In  conclusion,  we  would  call  the  attention  of  our  far- 
mers to  the  improvement  of  their  swamps  for  natural  meadows. 
It  can  be  shown,  that  such  lands  are  most  valuable  for  this 
purpose,  and  may  be  made  to  yield  a  profit  from  twenty  to 
fifty  dollars  per  acre  annually. 

Sect.  2.  Relation  of  Farm  Stock  to  the  Cultivated  Crops. 

The  subject  of  farm  stock,  is  intimately  related  to  the  cul- 
tivation of  farm  crops.     The  one  cannot  well  flourish  without 


*  vSee  Fourth  Report  of  the  Agriculture  of  Massachusetts,  p.  233. 


FARM  STOCK  AND  CULTIVATED  CROPS.        347 

the  other.     The  suggestions  which  we  would  make,  relate  to 
the  mode  of  improving  stock. 

What  then  is  the  best  method  of  improving  the  farm  stock  ? 
We  answer,  by  improving  the  farm  crops.  The  thrift  of  farm 
stock  depends  more  upon  a  proper  attention  to  the  prepara- 
tion of  proper  food,  than  to  any  other  circumstance.  Why 
is  it,  that  farmers  must  send  to  Saxony  for  sheep,  to  Berk- 
shire for  swine,  to  Durham  or  Yorkshire  for  cattle,  and  to 
some  other  foreign  country  for  seeds  1  simply  because  the 
farm  is  not  attended  to,  because  the  soils  and  crops  are  neg- 
lected. There  is  neither  the  variety,  quantity  or  quality  of 
products,  which  are  necessary  to  improve  native  breeds,  or  to 
keep  up  the  thrift  and  perfection  of  those  which  are  imported. 
The  consequence  is,  that  the  imported  and  improved  animal 
or  plant  will  flourish  for  a  while,  but  will  gradually  deterio- 
rate, until  they  both  sink  below  the  native  stock  ;  a  new  im- 
portation must  be  made,  and,  in  all  such  cases  an  extrava- 
gent  price  paid.  Is  it  not  a  just  subject  of  reproach  to  New 
England  farmers,  that  they  should  thus  be  made  the  dupes  of 
speculation,  with  regard  to  their  farm  stock ;  while  they  have 
a  soil,  climate  and  sources  of  improvement,  so  favorable 
for  the  rearing  of  stock,  that  they  ought  to  be  r  pattern  for  the 
rest  of  the  world  ? 

It  is  a  law  of  the  animal  and  vegetable  kingdoms,  that  neg- 
lect will  produce  deterioration.  This  may  not  be  percepti- 
ble the  first  generation  ;  the  second  will  begin  to  show  it ;  the 
third  still  more.  And  in  the  course  of  ten  or  twelve  genera- 
tions, the  reproductive  and  vital  powers  will  be  either  wholly 
exhausted,  or  require  double  feeding,  to  enable  them  to  per- 
form their  oflices. 

On  the  other  hand,  when  the  animal  or  the  vegetable  has 
thus  become  deteriorated,  proper  attention  will  not  reme- 
dy the  evil  in  a  single  generation.  The  progress  of  improve- 
ment is  slow ;  and  hence  it  is,  that  improved  stock,  and  im- 
proved seeds,  result  from  a  long  course  of  careful  culture.    It 


348  PRACTICAL  AGRICULTURE. 

requires  at  least  as  long,  if  not  longer,  to  restore  their  wasted 
energies,  as  it  does  to  destroy  them. 

The  great  mistake  with  most  farmers  is,  that  they  attempt 
to  cultivate  too  much  land.  They  are  not  impressed  with  the 
importance  of  investing  capital  in  their  farms  and  farm  stock 
for  future  use.  They  look  not  to  a  future  and  permanent 
fertility  and  thrift,  but  to  an  immediate  gain.  The  best  stock 
are  the  fattest,  and  of  course  will  bring  the  most  money  in 
the  market  ;  they  of  course  are  sold  off,  and  disposed  of  by 
the  butcher  and  his  customers.  The  best  hay  must  go  to 
market,  for  that  which  is  inferior  will  keep  the  stock  alive. 
The  sure  remedy  for  these  evils,  is  to  have  no  inferior  pro- 
ductions ;  and  then  we  may  hope  to  send  our  live  stock  and 
seeds  to  other  countries,  instead  of  bringing  theirs  to  our 
own. 

It  is  not  intended  by  these  remarks  to  dissuade  farmers  from 
attending  to  the  improvement  of  their  farm  stock,  but  simply 
to  point  out  the  best  mode  of  improvement ;  and  to  show  the 
folly  of  attempting  to  retain,  for  any  length  of  time,  the  per- 
fection of  any  improvement  in  stock  or  crops,  without  at- 
tending to  the  preparation  of  food  for  them. 

The  true  method  of  improving  stock,  is  to  improve  the 
farm  ;  so  as  to  retain  any  advance  that  is  made,  rather  than 
to  be  constantly  running  out  one  kind  of  stock,  and  intro- 
ducing new  kinds. 

There  is  one  great  defect  in  the  mode  of  introducing  new 
stock  ;  but  one  or  two  of  a  kind  are  first  introduced.  These 
are  deteriorated  by  mixing  with  those  whose  reproductive  en- 
ergies are  weakened  or  exhausted.  By  this  course,  the  far- 
mer expects  to  procure  a  new,  and  better  breed  !  The  prac- 
tice of  farmers  in  this  respect,  reminds  us  strongly  of  the  reso- 
lutions passed  by  the  Irish  court :  "  Resolved,  that  we  build 
a  new  jail.  Resolved,  secondly,  that  the  new  jail  be  made 
from  the  old  one.  Resolved,  thirdly,  that  the  old  jail  remain 
standing,  till  the  new  one  is  built." 


HORTICULTURE.  349 

Fanners  resolve  to  make  new  breeds.  They  then  resolve  to 
make  them  out  of  their  old  breeds  ;  and  then  resolve  to  let  their 
old  breeds  remain  just  as  they  are,  until  the  new  breeds  are 
formed.  A  far  better  series  of  resolutions  would  be  to  re- 
solve, 1.  to  understand  what  their  crops  require;  2.  to  till  less 
land,  and  till  it  better  ;  3.  to  furnish  for  their  farm  stock  bet- 
ter provisions ;  and  finally,  retain  for  farm  purposes  the  best 
fodder,  the  best  seeds,  and  the  best  stock. 

We  would  remark,  in  conclusion,  that  there  are  other  ani- 
mals, aside  from  those  domesticated  by  the  farmer,  which 
bear  an  important  relation  to  the  cultivated  crops  ;  we  refer 
particularly  to  foxes  and  crows;  as  there  is  in  many  places, 
a  bounty  paid  by  the  State  for  their  destruction.  It  would  be 
far  wiser  policy,  to  expend  the  same  bounty  for  their  protection. 
A  single  fox  in  a  meadow  will  often  save  a  ton  of  hay  in  one 
season,  by  destroying  the  mice ;  while  crows,  and  other  birds 
perform  an  equally  valuable  service,  by  destroying  seeds,  worms 
and  insects,  which  would  otherwise  injure  or  destroy  the  crops. 


CHAPTER  IX. 


HORTICULTURE. 


Horticulture  is  so  far  a  branch  distinct  from  Agriculture, 
that  it  has  not  only  received  a  characteristic  name,  but  is 
generally  treated  of  by  writers  in  a  separate  treatise.  We 
should  have  said  nothing  upon  the  subject  in  this  work,,  but 
for  the  fact  that  a  few  suggestions  might  be  useful  to  the 
common  farmer,  who  does  not  make  gardening  a  particulat 
business,  but  wishes  to  understand  several  important  processes 
and  principles  connected  with  the  art.  It  should  be  re- 
marked, too,  that  the  most  important  natural  laws  apply  alike 


350 


HORTICULTURE. 


to  Agriculture  and  Horticulture  ;  and  that  a  few  suggestions 
here,  may  emhrace  what  would  require  a  separate  book  to  un- 
fold without  such  connection.  It  is  to  be  hoped,  therefore,  that 
what  we  may  be  able  to  say  on  this  branch  of  the  subject, 
will  not  be  wholly  out  of  place,  and  will  contribute  to  the  ad- 
vancement of  an  art  which  is  every  day  becoming  more  and 
more  important.  The  subject  may  be  treated  of  under  the 
following  heads.  1.  Selection  of  seeds,  and  the  preservation 
and  improvement  of  races.  2.  Propagation  of  species,  by 
seeds,  eyes,  cuttings,  grafting  and  budding.  3.  Processes  of 
pruning,  training,  potting  and  transplanting. 

Sect.  1.  Selection  of  Seeds,  and  Propagation  and  Improve- 
ment of  Races. 

The  quantity  and  quality  of  vegetable  productions  depend 
as  much  upon  the  proper  selection  of  seed,  as  upon  any  one 
operation  of  the  rural  art.  This  is  an  important  point  for  the 
attention  of  the  common  farm  ;  but  indispensable  to  the  suc- 
cess of  the  gardener. 

I.  The  maturation  of  the  seed  is  a  vital  action,  and  generally 
proceeds  without  any  difficulty,  when  plants  are  left  to  their 
natural  soil,  climate  and  culture.  But  cultivated  plants  often 
fail  to  mature  their  seeds;  or,  if  they  are  matured,  their  vital 
powers  are  weak,  and  they  produce  but  sickly  offspring. 
The  causes  of  sterility  are, 

1.  The  unnatural  development  o^  some  organ  near  the  seed 
vessels,  by  which  the  nourishment  designed  for  the  seed  is 
withheld.  Instances  of  this  are  found  in  the  pear,  pine-apple 
and  plantain.  The  nourishment  goes  to  the  fruit ;  in  which 
case  a  portion  of  it,  or  of  water,  should  be  withheld,  so  that 
the  seed  may  receive  its  proportion.  Hence  it  is,  that  some 
plants,  as  the  pine-apple,  will  only  mature  their  seeds  in  a 
poor  soil.  The  tubers  of  potatoes  often  abstract  nourishment 
from  the  seed,  and  the  seed  from  the  tuber  ;  the  same  is  true 


IMPROVEMENT  OF  RACES.  351 

of  other  roots.     Hence,  if  seeds  are  required  of  such  plants, 
they  will  be  much  more  perfect  if  the  tubers  are  removed. 

2.  Deficiency  of  pullen.  Some  plants  become  so  debili- 
tated by  cultivation,  that  the  pollen  of  the  stamen  will  not  fer- 
tilize the  stigma  of  the  pistil.  In  this  case,  the  only  remedy 
is  to  bring  pollen  from  some  more  vigorous  plant,  and  apply 
it,  by  artificial  means  ;  a  process  only  applicable  to  garden 
plants. 

3.  A  moist,  cold  atmosphere,  will  prevent  the  pollen  from 
being  formed  ;  and,  if  formed,  from  being  thrown  upon  the 
stigma.  The  fertilizing  influence  takes  place  only  when  the 
plant  is  exposed  to  the  warm  dry  air.  Sometimes  the  pres- 
ence of  insects  is  necessary  to  convey  the  pollen  to  the  stig- 
ma ;  and  if  they  are  absent,  sterility  will  follow. 

4.  The  most  frequent  cause  of  sterility  is  the  monstrous 
condition  of  the  floioers  of  many  cultivated  plants.  The  flow- 
ers are  nothing  but  modifications  of  the  leaves  ;  the  stamens 
become  florets  in  the  course  of  cultivation,  as  always  happens 
in  double  flowers.  Now  it  is  evident,  that  when  the  stamens 
are  thus  all  changed,  they  cannot  secrete  pollen,  and  of  course 
there  is  nothing  to  fertilize  the  stigma.  The  stigma  itself, 
also,  becomes  changed.  This  can  be  remedied  only  by 
planting,  near  by,  the  same  species  of  plant  which  have  either 
stamens  or  pistils,  as  the  case  may  be,  and  the  requisite 
quantity  of  pollen  may  be  thus  furnished. 

5.  Many  cultivated  plants  are  grown  in  a  climate  different 
from  that  in  which  they  grow  naturally.  The  process  of 
watering,  also,  often  exposes  the  flowers  and  fruit  organs  to 
decay. 

Such  are  some  of  the  causes  of  the  sterility  of  plants;  and 
it  is  evident,  that  if  these  and  other  causes  do  not  operate 
wholly  to  prevent  seeds  from  ripening,  they  may  weaken  their 
power  of  reproduction.  As  weak  seeds  will  produce  weak 
plants,  resource  should  be  had  to  every  means  possible,  to 
give  the  highest  degree  of  life  and  vigor  to  these  indispensa- 


352  HORTICULTURE. 

ble  bodies.  Generally,  the  best  seeds  may  be  found  by  ex- 
amination ;  the  plumpest  and  most  completely  formed  should 
be  selected.  Or  they  may  be  floated  on  water,  and  those 
only  selected  which  sink  to  the  bottom. 

But  this  mode  is  not  the  best  possible  one  for  garden  seeds 
and  fruits  ;  for  the  vital  principle  in  seeds  may  be  increased 
by  removing  branches  or  fruits  that  are  near  ;  by  exposing 
the  seed  vessels  to  light ;  and  by  prolonging  the  period  of 
ripening. 

It  is  a  well  established  law,  of  animals  and  vegetables,  that 
an  unhealthy  parent  produces  a  diseased  offspring ;  the  seed 
will  take  after  its  parent.  A  vigorous  parent  will  yield  "  a 
healthy  progeny  in  all  their  minute  gradations  and  modifica- 
tions ;  hence  varieties  and  monstrosities  are  matters  of  gene- 
ration and  constant  reproduction."  If  seeds  are  to  be  sown 
immediately,  it  is  better  that  they  should  not  be  quite  ripe; 
for  there  are  two  periods  in  the  latter  part  of  the  organization 
of  seeds,  one  before  they  are  fully  matured,  when  they  pos- 
sess the  germinating  power,  and  will  flourish  well  if  immedi- 
ately sown  ;  and  the  other,  when  they  are  fully  ripe,  in  which 
case  they  lay  up  a  large  portion  of  carbon,  and  will  not  ger- 
minate until  some  of  it  is  abstracted  by  the  decomposition  of 
water.  Hence,  if  seeds  are  to  be  kept  for  any  considerable 
time,  they  should  be  perfectly  ripe,  and  kept  perfectly  dry. 
They  will  then  preserve  their  vital  powers  entire,  for  a  great 
length  of  time.  The  vital  energy  differs  in  this  respect  from 
1  to  17  hundred  years  or  more,  p.  42. 

If  seeds  are  to  be  packed  up,  it  is  best  to  put  them  in  coarse 
paper,  enclosed  in  coarse  canvass  bags  and  exposed  to  the  air, 
the  seeds  being  made  perfectly  dry  before  packing. 

II.  The  prescrvatian  of  the  races  or  varieties  of  plants  by 
seeds,  involves  many  important  laws  of  vegetable  life,  which 
are  of  great  interest  to  the  practical  gardener.  This  process 
is  applicable  to  all  plants  ;  but  is  more  important,  and  more 


PRESERVATION  OF  RACES.  353 

difficult  in  the  case  of  annual  plants,  which  comprise  those 
most  cultivated  by  the  farmer  and  the  gardener. 

It  is  the  general  law  of  seeds,  to  propagate  species  only  to 
which  they  belong ;  hence,  we  cannot  rely  upon  any  par- 
ticular variety  of  the  species.  There  is,  however,  a  tendency 
to  produce  a  seedling  more  nearly  resembling  the  parent,  than 
any  other  variety  of  the  species.  There  will,  therefore,  be  a 
majority  of  plants  either  like,  or  better  than  the  parent.  By 
selecting  these  for  seed  the  second  year,  and  obtaining  in 
each  successive  year  those  most  resembling  the  original  seed, 
the  variety  will  be  in  time  established.  Every  cultivated  grain 
has  doubtless  passed  through  successive  stages  of  perfection 
in  a  similar  way,  and  a  new  habit  has  hecomo,  jixed.  See  p.  324, 

It  is  easy  to  learn  how  different  varieties  are  produced  ; 
early  or  late  varieties,  for  example.  If  a  plant  has  been  cul- 
tivated for  years  in  a  warm,  dry  soil,  where  it  ripens  in  60 
days,  it  will  acquire  an  excitable  habit ;  and  when  sown  in  a 
colder  soil,  will  for  a  season,  mature  its  fruit  much  earlier. 
"The  reverse  will  happen  to  an  annual  from  a  cold,  wet 
soil."  But  in  both  cases,  if  the  plant  be  continued  in  the 
same  soil,  it  will  change  its  habits ;  hence,  seedsmen  ob- 
tain seed  from  warm,  dry  soils,  for  their  early  vegetables ; 
hence  too,  we  may  raise  on  cold  lands  certain  crops,  as  barley 
or  Indian  corn,  provided  the  seed  be  procured  from  warm, 
and  dry  soils.  But  how  can  these  varieties  be  preserved 
as  their  tendency  is,  to  revert  back  to  their  wild  state  ? 

1.  The  best  mode  of  preserving  the  variety  is,  to  transplant 
the  plant  shortly  before  it  goes  to  seed.  By  this  means  the 
character  of  the  variety  will  remain. 

2.  Another  mode  of  preserving  the  variety  is  to  cultivate 
the  crop  so  far  from  any  other  crop  of  the  same  species,  that 
there  may  be  no  intermixture  of  the  pollen.  This  substance 
is  conveyed  a  considerable  distance  by  the  winds,  and  by  in- 
sects ;  hence,  seeds  should  not  be  saved  from  one  or  two  in- 
dividuals standing  alone  in  a  garden,  as  bees  and  other  insects 

30 


354  HORTICULTURE. 

will  be  more  likely  to  introduce  the  pollen  of  the  same,  or 
similar  species  from  a  distance. 

III.  Improvement  of  varieties  or  races.  The  remarks  al- 
ready made,  apply  to  the  improvement  of  the  races  or  varie- 
ties. A  fixed  improvement  in  the  quality  of  the  produce  of  a 
plant,  can  be  obtained  only  in  two  ways  ;  eiihex  accidentally ^ 
or  by  the  process  of  muling. 

1.  Accidental  varieties  often  spring  up,  we  know  not  why, 
but  when  they  occur,  they  indicate  a  change  in  the  organ, 
which  is  sometimes  propagated  in  the  seed.  The  nectarine 
may  thus  have  been  produced  from  the  peach. 

2.  But  the  most  direct  means  of  establishing  new  breeds  or 
varieties,  is  by  a  process  called  cross-breeding  or  muling; 
that  is,  by  selecting  the  most  vigorous  plants  of  two  varieties, 
and  putting  the  pollen  of  the  one  upon  the  stigma  of  the  other. 
A  new  variety  will  thus  be  produced,  which  may  be  perpetu- 
ated as  above  described.  In  this,  way,  nearly  all  our  varie- 
ties of  squash  and  mellon  are  produced;  and  some  of  the 
most  gaudy  and  beautiful  flowers  which  adorn  our  gardens. 
There  is  no  end  to  the  different  varieties  which  may  be  form- 
ed by  this  process. 

Sect.  2.    Propagation   hy  Eyes,  Cuttings,   Grafting  and 
Budding. 

The  natural  mode  of  propagating  plants,  is  by  means  of 
their  seeds ;  but,  as  we  have  seen,  we  cannot  always  rely  up- 
on that  mode  of  continuing  the  same  variety.  Hence,  propa- 
gation by  other  modes  has  been  resorted  to,  as  the  most 
certain  means  of  preserving  and  continuing  any  variety  de- 
sired. These  modes  recommend  themselves  to  our  attention 
by  another  circumstance  ;  the  time  required  to  procure  the 
fruit  from  any  species  is  much  less,  than  when  the  seed  is 
employed. 

Annual  plants  must  be  propagated  by  their  seeds,  or  by  their 
tubers.   Biennial  and  perennial  plants,  may  generally  be  pro- 


PROPAGATION  BY  EYES,  CUTTINGS,  ETC.        355 

pagated  in  a  much  more  expeditious  manner  by  other  modes. 
Some  of  these  methods  will  form  the  subjects  of  this  section. 

I.  Propagation  by  eyes  and  buds.  The  propagation  by 
any  other  means  than  by  seeds,  depends  upon  the  presence  of 
leaf-buds,  or  what  are  technically  called  ''  fj/cs,"  which  are 
in  reality,  the  rudiments  of  branches  attached  to  the  stem  or 
tuber.  These  eyes  are  capable,  under  certain  conditions,  of 
producing  new  parts,  of  exactly  the  same  nature,  as  those 
from  which  they  sprung. 

Sometimes,  as  in  the  lily,  they  separate  from  the  plant,  and 
take  root,  producing  an  independent  plant ;  at  others,  they 
remain  on  the  stem,  and  send  out  branches,  flowers  and  fruit. 

In  theory,  all  plants  appear  capable  of  being  propagated  in 
this  way.  But  the  fact  is,  that  the  vital  power  of  buds  is  suf- 
ficient in  only  a  few  plants,  to  enable  us  to  be  successful ; 
only  two  are  by  this  practice  re-produced ;  these  are  the 
potato  and  the  vine.  The  method  of  propagation  by  the 
former,  is  too  well  known  to  need  description  ;  that  of  the 
latter,  is  as  follows.  The  eye,  with  a  small  portion  of  the 
stem,  is  commonly  taken,  and  placed  in  earth,  with  a  bot- 
tom heat  of  75°  or  80°,  in  a  damp  atmosphere.  In  a  short 
time,  it  shoots  upwards  into  a  branch,  and  sends  down  roots 
to  establish  itself  in  the  soil.  It  is  necessary,  that  a  consid- 
erable portion  of  the  albumen  should  be  planted  with  the  eye 
in  this  case,  as  the  bud  itself  does  not  contain  matter  suffi- 
cient for  its  development ;  this,  it  must  obtain  from  the  stalk  ; 
and,  if  the  quantity  is  increased,  that  is,  if  the  whole  vine  is 
buried,  the  sprout  is  much  more  vigorous.  There  are  a  few 
cases,  in  which  the  buds  are  fixed  in  embryo  upon  the  leaves, 
so  that  new  plants  may  be  propagated  from  them,  but  this 
mode  is  never  resorted  to  in  practice,  unless  it  be  in  some 
species  of  the  cactus. 

II.  Propagation  by  cuttings  or  sUj^s  is  the  most  common 
of  all  modes,  with  the  exception  of  grafting.  This  process 
depends  upon  the  eyes  or  buds,  and  consists  simply  in  cutting 


356  HORTICULTURE. 

off  a  branch,  inserting  it  in  fine  mould,  and  subjecting  it  to 
a  moist,  warm  air.  The  roots,  as  well  as  the  branches  come 
from  the  buds.  This  is  shown  by  the  fact,  that  the  vine, 
when  it  grows  in  a  warm,  damp  stove,  emits  roots  into  the  air 
which  proceed  from  buds.  Roots,  however,  seem  to  be  form- 
ed by  the  action  of  the  leaves  ;  branches  are  developments  of 
buds,  and  the  buds  are  maintained  by  the  matter  in  the  tree. 

Cuttings  may  be  placed  in  fine  mould  in  pots,  and  then 
either  subjected  to  a  moderate  hot-bed,  or  covered  with  glass 
and  exposed  to  the  direct  rays  of  the  sun. 

Layers  are  similar  to  cuttings,  the  only  difference  is  that 
they  are  attached  to  the  parent  branch,  until  the  roots  are 
established.  The  branch  is  bent  into  the  earth  and  half  cut 
through  at  the  bend,  and  as  soon  as  it  has  taken  root  it  is 
separated  from  the  parent  stalk. 

Suckers  are  branches  thrown  up  from  the  base  of  the  plant, 
and  are  one  means  of  continuing  and  propagating  the  same 
varieties. 

Ill,  Grafting  and  budding  are  operations,  which  consist 
in  causing  one  plant  to  grow  upon  the  stock  or  branch  of  an- 
other. This  process  differs  from  that  of  propagation  by  eyes 
and  cuttings,  only  in  the  circumstance,  that  in  the  former 
case,  a  part  of  one  individual,  containing  an  eye,  is  inserted 
into  another  of  the  same  family,  and  the  two  form  one  unique 
compound  individual ;  while,  in  the  latter  case,  the  eye  is 
made  to  send  its  roots  down  into  the  soil,  and  to  derive  its  sup- 
port from  it.  One  process,  is  the  inserting  of  an  eye  into 
another  tree,  the  other  is,  the  inserting  of  it  into  the  ground. 
The  object  of  these  operations,  is  the  same  as  that  of  layers, 
cuttings,  etc.,  to  continue  the  same  variety,  or  to  improve  it. 
It  is  particularly  applicable  to  those  plants  or  trees  (as  the 
apple,  pear,  peach,  etc.)  which  are  not  easily  propagated  in 
any  other  way.  There  are  also  many  advantages  secured, 
especially  in  the  character  of  the  fruit. 

J.  Some  varieties  or  species  are  nmch  more  hardy  than 


OPERATION  OF  GRAFTING. 


357 


others,  and  more  delicate  varieties  may  be  ingrafted  upon 
them,  and  partake  of  their  strength  and  vigor.  Thus  it  is, 
that  many  varieties  of  the  vine  are  propagated  ;  as  the  most 
choice  kinds  are  found  to  grow  better  upon  strong  robust 
stalks.  So  it  is  with  some  species  of  the  pear,  peach,  cher- 
ry, etc.  The  wild  plum  stock  is  prefered  for  the  insertion 
of  buds.     The  wild  apple  is  also  prefered  for  setting  grafts. 

2.  The  peculiar  qualities  of  some  plants  can  be  preserved 
only  by  this  process ;  thus,  for  example,  certain  varieties  of 
the  rose  will  become  plain,  if  they  are  not  budded  into  other 
stalks. 

3.  The  fruit  may  be  obtained  much  earlier,  and  sooner,  by 
these  processes  than  by  any  other.  In  fact,  Mr.  Knight  has 
succeeded  in  transfering  the  buds  of  one  plant  to  another, 
so  as  to  produce  fruit  and  flowers  the  same  season.  Fruit 
trees  do  not  require  more  than  three  years,  and  they  often 
will  become  fruitful  the  second  year  after  being  grafted. 

The  modes  of  performing  these  operations  are  various,  but 
with  regard  to  the  majority  of  fruit  trees,  it  is  a  very  simple 
process. 

Operation  of  grafting.  The  object  of  the 
operator  in  this  case,  is  to  cause  the  branch 
or  graft  of  one  tree  to  unite  with  the  stock  or 
limb  of  another  tree.  Varieties  of  the  same 
species  are  united  the  most  readily ;  genera 
of  the  same  natural  order  come  next,  beyond 
which  the  power  does  not  extend.  Thus  pears 
work  well  upon  pears  and  quinces ;  upon  ap- 
ples and  thorns,  they  will  grow,  but  not  so 
well ;  while  on  plums,  they  cannot  be  made  to 
grow. 

2.    Whip  grafting.     This  is  a  very  common 

kind  of  grafting  (Fig.  21).     "It  is  performed 

by  heading  down  a  stock,  paring  one  side  of 

it  for  the  space  of  an  inch  bare,  and  then  cut- 

30* 


21. 


358  HORTICULTURE. 

ting  obliquely  towards  the  pith  from  the  upper  end  of  the  par- 
ed part.  The  scion,  f ,  is  cut  obliquely  to  correspond  to  the 
part  pared,  d,  and  then  a  tongue  made  to  fit  into  the  slit  in 
the  stock.  Care  should  be  taken  to  have  the  bark  of  the  sci- 
on exactly  fitted  to  that  of  the  stock,  and  then  the  scion  may 
be  covered  with  a  cement  of  rosin,  beeswax  and  tallow,  and 
bound  firmly  together.  The  sap  will  pass  up  into  the  scion, 
and  its  buds  will  develope  themselves  ;  the  prepared  nutri- 
ment will  then  descend  and  cover  the  wound  where  they 
are  united.  This  process  is  said  to  be  far  superior  to  the 
process  most  common  with  us. 

2.  Crown  grafting.  This  process  con- 
sists simply  in  heading  down  a  stock  hori- 
zontally (Fig.  22),  splitting  it  open  in  the 
centre,  h,  and  then  cutting  one,  two  or 
more  scions,  a,  so  as  to  fit  in  exactly  like  a 
wedge ;  care  being  taken  to  have  the  bark 
of  the  scion  and  that  of  the  stock  exactly  co- 
incide. The  whole  is  then  covered  with 
clay,  or  with  the  cement  above  spoken  of,  and 
the  scion  is  held  in  its  place  by  the  force 
of  the  wood,  in  the  same  manner  as  a  wedge.  This  process 
often  leaves  too  large  a  wound,  and  the  parts  are  not  always 
healed  over  and  made  firm.  It  is,  however,  the  most  expedi* 
tious  way,  the  most  simple  and  generally  the  most  successful. 

3.  Saddle  grafting.  Lindley  recommends  Mr.  Knight's 
mode  of  saddle  grafting,  which,  although  more  tedious,  is 
preferable  to  either  of  the  preceding  modes.  It  consists  in 
paring  the  sides  of  the  stalk  obliquely  into  the  form  of  an 
inverted  wedge,  and  then  cutting  the  scion  so  as  to  slip  it  di- 
rectly into  the  stock,  the  bark  of  both  exactly  coinciding.  By 
this  mode,  the  greatest  quantity  of  surface  is  brought  into  con- 
tact, and  the  sap  can  pass  up  and  down  with  the  greatest  fa- 
cility. The  scion  must  be  kept  in  its  place  by  a  ligature, 
and  the  water  excluded   by  cement.     As  the  graft  stands 


OPERATION  OF  GRAFTING. 


359 


astride  the  stock,  it  is,  when  united  by  the  wood,  firm  and 
straight.  But  in  all  cases,  success  will  depend  upon  the  ex- 
act coincidence  of  the  scion  and  the  stock,  in  their  inner 
barks  and  alburnum,  in  which  the  sap  flows  up,  and  the 
cambium  down,  and  where  the  process  of  assimilation  takes 
place. 


4.  Budding  consists  in  introducing 


a  bud  of  one  tree  into  the  bark  of 
another.  The  process  is  as  follows  : 
An  incision  is  made  (Fig.  23), 
through  the  bark  to  the  wood,  and 
then  crossed  at  the  top  a  with  a  simi- 
lar incision.  A  bud  is  now  select- 
ed by  paring  it  from  the  branch,  tak- 
ing care  to  cut  a  small  quantity  of 
the  alburnum  directly  under  the  eye, 
and  a  portion  of  the  bark,  a.  This 
is  then  inserted  below  the  bark  of  the 
stock,  until  the  bud  is  in  contact  with 
the  wood,  and  the  upper  lip  of  the  wood  in  the  stock  is  made 
to  coincide  with  that  of  the  bud.  The  whole  is  then  bound 
by  a  ligature.  The  object  in  this  process  is,  to  bring  in 
close  contact  a  large  surface  "of  young  organizing  matter," 
and  as  the  bud  is  thus  freely  supplied  with  nutriment,  it  soon 
unites  by  the  edges,  and  the  following  spring  developes  itself 
in  the  form  of  a  branch.  The  period  for  budding  is  generally 
about  the  middle  of  August,  or  at  a  time  when  the  bark  will 
easily  peal  from  the  stock.  In  selecting  stocks  for  grafting 
and  buddmg,  regard  should  be  had  to  the  soil  and  climate. 


Sect.  3.    Pruning,  Training,  Potting  and  Transplanting. 

I.  Pruning.  The  object  of  pruning  is  to  remove  branches 
and  leaves,  so  as  to  contribute  to  the  beauty,  health  and  pro- 
ductiveness of  the  plant  or  tree. 


360 


HORTICULTURE. 


1.  The  effect  of  removing  a  branch,  is  to  turn  the  sap  into 
the  neighboring  organs,  or  into  some  other  part ;  hence  it  is 
necessary  to  cut  a  useless  branch  fully  off,  so  as  to  destroy  the 
buds  near  the  base.  If  this  is  not  done,  these  buds  will  put 
forth  several  branches,  instead  of  the  one  which  is  taken 
away.  When  the  nourishment  is  thus  driven  into  the  neigh- 
boring organs,  they  sometimes  throw  out  branches,  which  will 
bear  abundant  fruit  the  next  year;  this  is  the  fact  with  the 
filbert.  The  peach,  also,  may  thus  be  rendered  both  fruitful 
and  much  longer-lived,  even  in  climates  unfavorable  to  its 
growth.  Apples,  pears  and  plums  are  rendered  vigorous  and 
strong  by  pruning.  This  effect  is  sometimes  secured  by  sim- 
ply squeezing  the  ends  of  the  young  limbs,  just  so  as  to  pre- 
vent their  elongation,  and  to  direct  the  matter  to  other  parts, 
or  to  the  maturing  of  the  seed.  If  the  shoots  are  allowed 
to  increase,  the  buds  will  not  form  for  the  next  crop.  During 
the  ripening  of  the  fruit,  especially,  care  should  be  taken  that 
the  buds  and  sprouts  in  the  vicinity  are  removed,  or  twisted 
to  direct  the  nourishment  to  the  fruit. 

2.  The  effect  produced  upon  one  part  by  abstracting  an- 
other, is  seen  further  in  the  quantity  and  quality  of  the  fruit. 
If  all  the  fruit  of  a  plant  is  removed  from  it  one  year,  it  will 
be  more  abundant  and  of  a  better  quality  the  next  year. 
Hence  we  see  in  nature,  that  orchards  so  exhaust  themselves 
in  their  season  of  bearing,  that  they  are  obliged  to  rest  the 
next  year  to  recover  energy  for  a  succeeding  crop.  Of  two 
branches,  if  one  is  cut  off,  the  other  will  grow  with  more  vigor. 
This  doctrine  lies  at  the  foundation  of  all  the  processes  of 
pruning,  and  enables  the  gardener  to  equalize  the  crops  and 
the  rate  of  growth  of  all  parts  of  the  tree.  If,  for  example, 
when  orchards  are  disposed  to  bear  only  every  other  year,  a 
part  of  the  fruit  were  abstracted  in  the  bearing  season,  some 
would  be  produced  in  the  unfruitful  season  ;  and,  after  a  little 
time,  a  habit  of  producing  a  moderate  crop  might  be  induced 


REASONS  FOR  PRUNING.  361 

and  established.  This,  of  course,  vvouhi  be  more  valuable  than 
one  heavy  crop  once  in  two  years. 

The  utility  of  trimming  fruit-trees  and  vines  when  young, 
depends  wholly  on  the  principle  now  considered. 

In  pruning  some  trees  and  vines,  the  plant  is  exposed  to 
what  is  called  bleeding ;  this,  if  not  prevented  by  covering 
the  wounded  part,  will  injure  and  perhaps  destroy  the  plant. 
One  mode  to  avoid  this,  is  not  to  wound  such  trees  when  their 
sap  is  flowing  freely.  Another  is,  to  dissolve  some  gum  shel- 
lac in  alcohol,  and  with  a  brush  cover  the  wood  and  prevent 
the  issuing  of  the  sap. 

In  performing  the  operations  of  pruning,  reference  should 
be  had  to  the  character  of  the  tree.  Some  trees  bear  fruit  on  the 
branch  w4iich  grows  the  same  year,  as  the  walnut.  A  second 
class,  as  the  filbert,  grows  on  the  wood  of  the  previous  year ; 
while  a  third  class,  as  pears  and  apples,  are  produced  from 
branches  which  are  several  years  old.  Hence  different  parts 
should  be  removed  from  each  of  the  different  families. 

The  season  for  pruning  is  either  in  mid-winter  or  mid-sum- 
mer. The  object  of  the  former  method  is  to  thin  and  ar- 
range the  branches;  that  of  the  latter,  to  remove  superfluous 
branches  or  aid  in  ripening  the  fruit,  and  in  forming  the  fruit 
of  the  succeeding  year.  It  may  be  done  at  other  seasons,  as 
early  in  the  autumn,  or  when  the  tree  is  in  blossom  in  the 
spring.  It  should  never  be  done  when  the  sap  first  begins  to 
flow  in  the  spring,  because  the  tree  wants  all  its  leaves  to 
commence  the  process  of  nutrition  with  vigor. 

It  has  been  a  question  among  gardeners,  whether  trees 
which  are  transplanted  should  be  pruned  ?  This  question  is 
easily  settled  theoretically.  We  know  that  the  leaves  are 
wanted  to  enable  the  plant  to  put  forth  its  roots ;  for  the 
nutritious  matters  must  go  through  a  change  in  the  leaves, 
before  they  descend  to  the  roots.  Now  if  the  leaves  are  di- 
minished by  pruning,  the  power  of  the  transplanted  plant  to 
take  root  in  the  soil,  is  much  diminished.     The  roots  should 


362  HORTICULTURE. 

be  trimmed  rather  than  the  branches,  although  no  root 
should  be  removed  unless  it  is  mutilated.  If  young  trees, 
when  transplanted,  are  trimmed  at  all,  it  should  be  done  in 
the  fall,  when  the  quantity  of  nutrition  laid  up  in  them  ena- 
bles them  to  sustain  such  losses  as  they  must  suffer  in  the 
process. 

Root-pruning,  however,  may  be  advantageous  to  trees 
which  produce  leaves  rather  than  fruit ;  and  some  gardeners 
have  thus  rendered  their  trees  fruitful. 

There  is  a  peculiar  kind  of  pruning,  called  ringing,  that  is, 
the  removing  of  a  ring  of  bark,  at  certain  seasons,  for  the  pur- 
pose of  stopping  the  sap  as  it  descends  from  the  leaves,  and  of 
turning  it  either  to  the  formation  of  fruit-buds  or  fruit,  as  the 
season  may  be.  This  operation,  however,  although  it  often 
increases  the  quantity  and  quality  of  the  fruit,  endangers  the 
/life  of  the  tree,  and  is  rarely  resorted  to.  The  same  effect  is 
sometimes  produced  by  placing  a  heavy  stone  in  the  fork  of 
the  limbs.  By  the  pressure  it  exerts,  and  by  the  compression 
it  gives  to  the  limb,  it  obstructs  the  free  circulation  of  sap, 
and  thus  increases  the  quantity  of  fruit.* 

II.  Training  is  an  operation  wholly  artificial.  It  has  for 
its  object  the  placing  of  a  plant  in  a  position  different  from 
what  it  could  ever  attain  of  itself,  in  order  to  gain  the  advan- 
tage of  light,  heat  and  support.  Hence  plants  are  generally 
trained  or  made  to  grow  by  a  south  wall,  where  the  tempera- 
ture is  more  equable,  and  where  the  winds  are  shut  off  so 
that  perspiration  or  evaporation  (a  frequent  cause  of  injury) 
is  more  equal  and  moderate. 

1.  By  thus  exposing  a  tree  to  a  warmer  atmosphere,  the 
sweetness  of  the  fruit  is  nmch  increased  ;  hence  plums, 
pears  and  grapes  are  much  sweeter  grown  on  walls  with  a 
southern  exposure. 

2.  By  training,  the  circulation  may  be  impeded,  and  the 

*  Lindk>v. 


POTTING TRANSPLANTING.  363 

fruit  increased  in  quantity.  Thus  it  is  found,  that  when  the 
branches  are  made  to  grow  downward,  they  will  grow  less 
vigorously,  but  will  also  produce  much  more  fruit,  because 
the  circulation  is  thus  impeded. 

3.  In  the  case  of  grapes,  it  is  found,  that  the  fruit  is  in- 
creased, by  training  the  top  branches  at  a  great  distance  from 
the  root.  The  tops  of  tall  trees  are  more  fruitful  than  the 
side  branches,  owing  to  their  distance  from  the  roots. 

The  trees  which  are  benefited  by  training,  are  such  as  are 
properly  climbers,  as  the  grape ;  but  trees  whose  erect  pos- 
ture shows  that  they  were  made  to  be  rocked  by  the  storms, 
are  always  injured  by  this  process. 

III.  Potting  is  the  growing  of  plants  in  small  earthen  ves- 
sels or  tubs.  The  condition  of  the  roots,  in  this  case,  is  dif- 
ferent from  that  of  their  natural  position  in  the  soil.  This 
process,  for  most  plants,  is  wholly  unnecessary.  The  princi- 
pal use  of  it  is  to  give  a  start  to  some  plants,  at  a  period  when 
they  cannot  be  placed^n  other  conditions.  The  plant  will 
exhaust  the  soil,  which  must  be  changed  frequently,  or  they 
will  become  sickly.  If  plants  are  placed  in  large  tubs,  they 
will  flourish  much  better  and  for  a  longer  time.  The  cases 
where  potting  is  useful,  refer  to  rare  plants,  or  to  those  which 
will  not  endure  the  frosts  of  winter,  and  to  plants  which  are 
to  be  transplanted.  In  the  latter  case,  potting  answers  in- 
stead of  a  hot-bed. 

IV.  Transplanting.  This  is  an  important  process ;  and 
one  in  relation  to  which,  correct  practice  leads  to  the  most 
useful  results.  A  few  remarks  must  suffice  here,  upon  the 
transplanting  of  trees. 

These  relate  to  the  time  and  manner  of  performing  the 
operation.  In  our  country,  the  season  most  desirable,  is  the 
spring ;  and  during  a  moist  or  rainy  day.  In  some  coun- 
tries, the  fall  is  chosen,  because  the  evaporation  from  the  tree 
is  much  less  in  the  autumn,  and  early  part  of  winter  than  in 
the  spring.     But  the  frosts,  by  up-heaving  the  earth  and  the 


364  HORTICULTURE. 

roots,  do  more  injury,  than  can  arise  from  the  different  states 
of  the  atmosphere. 

It  has  been  customary  to  prune  trees,  at  the  time  of 
transplanting ;  but  it  is  at  least  a  very  doubtful  practice. 
The  branches  contain  the  leaves  which  are  necessary  to  pre- 
pare the  nutriment  which  is  stored  up  in  the  autumn,  for 
assimilation.  If,  therefore,  we  cut  off  the  branches,  we  di- 
minish that  power  which  is  first  wanted  in  all  its  force,  to 
meet  the  demands  of  life  at  this  critical  period. 

But  the  most  important  point  to  be  attended  to  in  a  prac- 
tical way,  is  the  preparation  of  the  ground,  and  the  mode  of 
locating  the  individual  in  its  new  home.  For  most  trees,  the 
soil  should  be  rendered  mellow  and  rich,  for  a  considerable 
distance  around.  The  pits  should  be  made  from  3  to  10 
feet  across,  according  to  the  size  of  the  tree.  The  roots 
should  be  left  free,  to  extend  themselves  into  the  soil ;  and 
the  earth  around  the  stem  should  be  left  a  little  dishing,  to 
gather  up  the  water  that  falls.  It  is  also  desirable  to  fill  up 
the  pits  with  mould  and  ashes.  When  these  conditions  are 
properly  attended  to,  the  tree  will  be,  not  only  more  thrifty  at 
first,  but  the  influence  will  extend  often  through  the  whole 
period  of  life. 

There  are  many  other  points  on  the  subject  of  horticulture, 
which  are  important  for  the  professional  gardener  ;  especially 
the  management  of  green-house  plants.  But  as  these  are  of 
little  importance  to  the  farmer,  we  shall  here  close  the  sub- 
ject, and  with  it  our  book,  with  the  hope,  that  we  may  at 
some  future  period,  be  able  to  supply  its  present  defects. 


END. 


INDEX. 


Acid  acetic,  54 

apucrenic,  Co,  136,  217 

benzoic?,  118 

crenic,  (i5,  216 

citric,  118 

gallic,  118 

humic,  65,  215 

hydrochloric,  168 

malic,  118 

nieconic,  118 

nitric,  48 

oxalic,  117 

phosphoric,  168,  176 

prussic,  119 

silicic,  167,  175,  204 

sulphuric,  168,  176 

tannic,  118 

tartaric,  118 

ulmic,  13'J 
Agricultural  Chemistry,  32 

Geology,  32 
Alkalies,  119 
Albumen,  31 
Aloes,  122 

Alumina,  167,175,206 
Aluminium,  180 
Alluvial  soil,  231,249 
Aluminous  soil,  244 
Almond,  132 
Ammonia,  20,  48,  80,  159 
Ammoniac,  122 
Amygdalin,  127 
Amylaceous  substances,  124 
Anise,  134 

Analysis  of  soils,  193 
Animal  bodies,  294 
Apple  thorn,  134 
Aqueous  rocks,  186 
Argillaceous  slate  soil,  238 
Argillaceous  rock,  188 
Artichoke,  129 
Arrow-root,  124 
Ashes,  317 
Asparagus,  131 
Eark,  31 
Barley,  132,332 
Barn-cellar,  288 
Bean,  small,  132 

kidney.,  132 


Beet,  128 

Beets,  :i35 

Belladonna,  130 

Biology,  29 

Bitter  principle,  127 

Blue  dye,  120 

Bones,  296 

Bone-dust,  296 

Brazil  wood,  121 

Broom- corn,  327 

Buckwheat,  332 

Bu*ding,  359 

Buds,  44 

Bulbs,  44,  129 

Calcareous  soil,  246 

Calcareous  spar,  185 

Caloric,  101 

Caoutchouc,  127 

Calcium,  180 

Cambium,  131 

Carbon,  48,  138 

Carbonate  of  magnesia,  166 
potash,  166 
lime,  167,  251,314 
Carboniferous  soils,  236 
Carrot,  128,  336 
Catalytic  force,  45 
Cattle  yard,  288 
Cells, 31 

Cellular  tissue,  30 
Chalky  soil,  2.'i5 
Chemical  affinity,  100 
analysis  of  soils,  198 
classification  of  soils,  242 
transformations,  45 
Chlorides,  319 
Cinchonia,  119 
Clay,  253 
Clay  slate  soil,  237 
Classification  of  soils,  230 
Clover,  340 
Cocoa-nut,  134 
Coffee  bean,  135 
Cohesion,  99 
Coloring  matters,  120 
Common  salt,  166,  213 
Compound  bodies,  44 
Compost  of  peat,  306 
Conglomerate  soils,  236 
31 


366 


INDEX. 


Conia  or  conicina,  120 

Cotton,  ]30 

Cotyledon,  44 

Cow  dung,  284 

Cow  grass,  312 

Cream  of  tartar,  118 

Cretaceous  soils,  235 

Crown  grafting,  358 

Cubebs,  133 

Cucumber,  134 

Culm,  58 

Cultivator,  323 

Cuttings,  56 

Dates,  J  35 

Decay,  281) 

Decaying  plants,  190 

Diastase,  ]25 

Diseases  of  wheat,  328 

Draining,  286 

Drains,  258 

necessity  of,  260 

Drill-barrow,  235 

Electricity,  107 

Emetina,  120 

Emulsin,  126 

Endosmonieter,  108 

Endosmose,  108 

Epidermis,  31 

Epsom  salts,  166 
Essential  salt  of  lemons,  118 
Evaporation,  96 
Excitability,  36 
Exosinose,  1  JO 
Extractive,  127 
Extract  of  humus,  137 
Fallow  crops,  265 
Feldspar,  184 
Fermentation,  289 
Feathers,  296 
Fixed  oils,  121 
Flax,  130 
Fox-glove,  131 
Fungin,  125 
Galbanum,  122 
Gamboge,  122 
Garlic,  129 
Geates,  219 

Geine,65,  138,  153,156 
Gentian,  128 
Germination,  49 
Ginger,  129 
Glacial  soils,  233 
Glue,  296 


Gluten,  122 

Gneiss,  187 
soil,  246 

Gooseberry,  132 

Grain  insect,  329 

Grafting,  357 

Granite,  180 
soil,  240 

Grapes,  132 

Gravity,  98 

Graywacke,  188 

Green  crops,  267 

Growing  plants,  191 

Guano,  293 

Gum  bassora,  125 
resins,  122 
tragacanth,  125 

Gums,  125 

Hair,  295 

Hartshorn,  48 

Hemp,  130 

Hessian  fly,  329 

Hog  manure,  287 

Hoofs,  295 

Hops,  135 
Hornblende,  185 
rocks,  188 
rock  soil,  241 

Horns,  295 
Horse   radish,  128 
Horticulture,  349 
Humin,  05,  135 
Humus,  57,  138 
Ice,  92 

Igneous  rocks,  1S6 
Improvement  of  races,  350 

varities,  354 
Indian  corn,  124,132,324 
Insoluble  geine,  224 
Inter-cellular  canals,  30 
Ipecacuana,  129 
Irrigation,  2()2 
Irritability,  37 
Iron,  180 

Isatis  tinctoria,  131 
Isochimenal  lime,  104 
Ismorphism,   168 
Lsotheral  lime.  104 
Jalap,  128 

Juniper  berries,  134 
Lac,  121 
Lava  soils,  241 
Layers,  56 


INDEX. 


367 


Leached  ashes,  318 

Leaves,  130 

Legumin,  127 

Lentiles,  132 

Liber,  31 

Light,  105 

Light  carbureted  hydrogen,  83 

Lignin,  125 

Litne,  Uw,  174,  207 

Limestones,  \6ti 

Liiuestone  soil,  238 

Loamy  soils,  249 

Log  wood ,  121 

Lucerne,  343 

Madder,  120 

Magnesia,  160 

Manna,  124 

Magnesium,  179 

Maize,  132 

Manganese,  160,209 

Mangel  VVurtzel,335 

Mango,  132 

Mechinical  analysis  of  soils,  195 

Medullary  rays,  31 

Mica,  lb4 

Mica  slate,  187 

Mica  slate  soil,  239 

Mildew,  329 

Mixed  manures,  284 

Muriates,  lo3 

Myrrh,  122 

Nails,  2115 

Naked  fallows,  265 

Narcotina,  119 

Neutral  substances,  123 

Nicotina.  120 

Night  soil,  287 

Nitrate  of  potash,  166,  313 

Nitrate  of  soda,  166.  313 

Nitrates,  312 

Nitre,  166 

Nitrogen,  48,158 

Nutmeg,  134  • 

Oats,  132,331 

Olibanum,  123 

Onion,  129 

Oolitic  soils,  236 

Opium,  123 

Orange.  132 

Orchard  grass,  345 

Organized  body,  130 

Organic  attraction,  39 

Organic  affinity,  39 


Organic  constituents  of  soils,  215 

Oxalate  of  lime,  118 

Oxalate  of  potassa,  118 

Oxides  of  manganese,  167 

Oxygen,  47,  73 

Pan II ma,  20 

Parsnip,  337 

Pear,  132 

Peas,  132 

Peat,  304 

Peat  alluvial  soils,  232 

Peaty  soils,  247 

Peat  ashes,  318 

Pepper,   132— Cayenne,  183 — Ja- 

njaica,  183 
Peroxide  of  iron,  167 
Petals,  59 
Phosphates,  183 
Pigeons'  dung,  294 
Plant,  30 
Plumula,  44 
Pollenin,  126 
Pomegranate,  129 
Pond  mud.  304 
Pores,  31 
Porphyry,  241 
Potash,  166,  211,71 
Potassium,  179 
Potato,  333,  129 
Potting,  363 
Poudrette,  293 
Practical  agriculture,  324 
Preservation  of  races,  352 
Pressure  of  the  air,  89 
Primary  soils,  237 
Printers'  ink,  121 
Propagation  by  buds — by  cuttings 

hy  eyes — by  layers — by  slips — 

by  suckers,  355,  356 
Proper  vessels,  30 
Proximate  analysis,  114 
Proximate  principles,  114 
Pruning,  359 
Putrefaction,  81,  289 
Pyrites,  186, 189 
Quartz,  183 
Quinine,  119 
Radicle,  44,  53 
Rattlesnake  root,  128 
Red  clover,  341 
Red  dyes,  120 
Red  top,  345 
Resins,  122 


368 


INDEX. 


Rhubarb,  128 
Rice,  132 
Rocks,  J80 
Roller,  'S22 
Root  crops,  278 
Root  culture,  280 
Roots,  J  28,  58 
Rotation  of  crops,  271 
Rotation  of  fields,  280 
Rust,  328 
Ruta  baga,  337 
Rye,  330,  131 
Rye  grass,  346 
Saddle  grafting,  358 
Saffron,  130 
Salts,  213 

Saliferous  soils,  236 
Saline  manures,  312 

application  of,  320 
Sand,  252 
Sandstones,  188 
Saponin,  126 
Sarsaparilla,  129 
Sea  weed, 303 
Secondary  soils,  235 
Seeds,  131 
Senna,  130 
Serpentine,  185 
Sheep  manure,  287 
Sienite  soil,  240 
Silicates,  181 
Siliceous  soils,  243 
Silurian  soils,  236 
Slacked  lime,  167 
Slaty  soil,  237 
Smut,  32!) 
Soda,  173,  166,213 
Sodium.  179 
Soil,  57' 
Solan  um,  120 
Soluble  geine,  218 
Soot,  2i)7 
Spent  lye.  209 
Spiral  vessels,  31 
Squills.  129 
Starch.  124 
Stem,  58 
Strychnina,  120 
Sub-soil,  58 
Suckers,  56 
Sugar,  123 

Sulphate   of  iron,   319 — of  lime, 
of  magnesia  and  soda,  166,  167 


I  Swamp  muck,  304 
Sweet  flag,  128 
Talc,  ltf4 
Talcose  slate,  188 
Talcose  soil,  239 
Tall  oat  grass,  348 
Tamarinds,  133 
Tapioca,  124 
Tartar  emetic,  118 
Tea,  131 

James,  131 

Paraguay,  131 
Tertiary  soils,  234 
Tillage,  66 
Tissue,  30 
Timothy,  344 
Tobacco,  131 
Trachyte  soil,  241 
Transplanting,  363 
Trappean  rocks,  188 

soils,  241 
Turnip,  336,339 
Turnip  beet,  336 
Ulmin,l39 

Ultimate  analysis,  115 
Urea,  300 
Urine  of  the  cow,  300 

horse,  301 

of  man,  301 
Utility  of  lime,  317 
Valerian,  128 
Vascular  tissue,  30 
Vegetable  albumen,  126 

mould,  65 
Vinegar,  118 
Vitality,  nature  of,  38 
Vital  principle,  29 
Viscin,  126 
Volatile  oils,  122 
Vortex,  30 
Water,  92 
Wheat,  327,  131 
Whip  grafting,  357 
White  clover,  353 
White  rochelle  salt, 
Wire- worm.  339 
Wood,  31,  130 
Wool,  2!'6 
Yellow  dye,  121 
Yellow  turnip,  339 
Zein,  126 


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